Dunno about Baliblinds but HunterDouglas Architella honeycomb shades claim an industry leading R4.3. A rule of thumb is that an air space is good for R1, so the Bali blind would be R2 until demonstrated otherwise. Builditsolar.com has numerous links to energy efficient window treatments here: http://www.builditsolar.com/Projects/Conservation/conservation.htm#WindowTreatments

http://www.warmcompany.com/wwtech.html claims R5.4 in a curtain combining insulation, mylar radiant barrier, polyethylene infiltration/vapor barrier and magnetic seals at the edges.

http://www.sailshadeyourhome.com/ claims Low E built into the shade and R7.

Two caveats and one question mark: Blinds with radiant barriers may be less effective over modern Low E windows. Perhaps an engineer here can fill us in on the effectiveness of multiple radiant barriers. Also, blinds that seal to the window should have a vapor barrier on the warm side to limit condensation.

The builditsolar site has an excerpt from a book claiming that moderate looseness in fit isn't a major performance killer, but most academics say otherwise.

I was wondering how blinds that aren't sealed at the edges don't promote more convection.

Convection is a vertical flow due to differences in buoyancy of cold & warm air densities.  Open sides have some effect, but the effect is small (and the wider the window, the smaller the effect.)  Making the top & bottom air gaps very small will prevent any high-flow loops from getting started.  And windows aren't generally very tall, so stack effects driving convection won't be large without correspondingly large delta-Ts.

Yes, there will be more convection with loose fit, but the bulk of the performance benefit will remain. 100% of the radiated loss is stopped- way better than any low-e coating could.  Will a tight fit improve performance? Hell yeah! But will it cut the heat loss relative to a loose fit in half? Not even close...

But the effectiveness in a loose fitting shade will drop with higher delta-Ts- it'll retain more of it's full R value when it's 30F outside than when it's 0F out.  This isn't dissimilar to performance drops with batt insulation in wall cavities with higher delta-Ts. But whether the extra expense & complexity of edge seals kinda depends.  In the Canadian arctic, probably yes, in Maryland, probably not (from either a comfort or a fuel-cost point of view.)

Basically, most windows are just big low-R gaps in the insulation.  It doesn't take a perfect solution to cut the heat loss there by more than half.  Going with a perfect air seal might make bring 65% cut in heat loss up to more like a 75% cut, but either way the larger goal has been met.

About to commit heresy here .... If a radiant barrier in an insulating shade is more effective than Low E, why settle for Low E's degradation of SHGC in a passive solar design? Andersen Low E casements designed specially for passive solar (still a rarity among window mfrs) have a U factor of .28 and a SHGC of .47. Skip the Low E and you get U factor=.45 and SHGC=.60. (You give up R1.3 for 28 percent more solar throughput.)
Gray winters in Pa. complicate the picture. There are lots of winter days, particularly in Dec, when you won't see the sun even though you'd want the curtains up. But in my case, window choice is $ neutral because I would substitute free wood heat for passive solar when the sun isn't shining.
UCLA's Heed modeling software says I'll spend an extra $200/yr without Low E, assuming electric resistance heat, but there is no way to model for insulating, radiant curtains.
Yes, I realize I will spend 5 minutes a day raising and lowering roman blinds. Hey, if you are not willing to futz with it, passive solar isn't for you.

One thing to be careful of with non Low-E windows is UV protection. Clear glass can fade your furnishings very quickly without UV protection.

Bright clouds count on passive solar too.  Unless your shades are something like R8 or higher your heat gain through the unshaded U0.5 window will  exceed the heat loss during the middle part of a cloudy day unless it's either wicked-cold or (or fairly dark clouds.)  It doesn't take direct sunshine to find the balance, even if it needs direct sunshine to make up the entire heat loss from the house with just the south-facing windows.  According to the RESFEN model, low-E coatings or triple glazing on S windows at my central MA zip code would block more passive solar gain than they would lose over a winter even without movable insulation shutters or shades.  Low E is a net benefit for E, N, & W walls though.  I'm a bit surprised the HEED model shows something different for you(?).

The shades don't necessarily need to have radiant barrier in them to block 100% of the room-radiated heat. They just need to be infra-red aborptive on the conditioned space side, they don't need to be reflective.  The absorbed heat raises the surface very slightly, but it re-radiated the heat back to the room about as efficiently as it took it in, without passing it through the R-value of the shade itself.  Only when shade is very thin does the effect of the radiant barrier become a significant performance boost.  A low emissivity surface on the window side of the shade improves performance, but it's on the cool side of the shade, radiating less than the conditioned space walls.  The semi-isolated air gap between the shade  and the window (or within the shade, for the fan-fold types) is an insulating boundary layer, and most of the heat loss out of the window is conducted, not radiated.

There's a lot of smoke and mirrors (well, mostly mirrors :-) ) in the radiant barrier & low-E coating world.  If you have any infra-red opaque conductive insulation in the stackup the relevance of the radiant insulations evaporates quickly.  The presence of a radiant barrier or low-E coating imparts a fixed-fractional reduction of the heat transfer.  With a U0.5 (=R2) window it doesn't take much additional "real" insulation to cut that in half or more, at which point the low-E or radiant barrier is only reducing the fixed-fraction of the already much-reduced heat transfer.  30-40% reduction of a high heat transfer is a lot, but 30-40% of nuthin' is still nuthin'.  With window shades it's somewhere between high transfer & nuthin' (but in an attic with R30 blown cellulose w/ joist-tops buried, it's a lot closer to 30-40% of nuthin'.)

Even with Low E, I plan to keep the furniture and its occupants out of direct sunlight. The windows start four feet up in a room with a 10.5 foot ceiling. The major seating will be under the windows looking in, with the glare rather than against it.
If the sun is still too intense on bright days, Plan B is interior frosted glass shutters.

Thx Dana. No Low E it is, assuming the local code officials get over being properly horrified. Have you noticed that the energy tax credits require SHGC =/<.30 whether it makes sense or not? Passive solar is underrated and overlooked IMHO.
But extremely dependent on the specific site. HEED isn't modeling my house correctly because my windows wrap around from south to west. West windows work in my case because there are trees and a mountain back there shading the house by late aft.