Did I mention I have a headache?..lol :-)

Thanks Dana...I'm still trying to dwindle down whats going to be a acceptable tradeoff of cost versus return for my home. The local ccSPF installer quoted about $6000 for 3" on the underside of the rafters. I want that for the strength and air/vapor sealing. Now...where & what type of insulation to add for the additional R-Value I feel might be needed.

3" of ccSPF is about R19

Next..another 3-4" of spray cellulose on the underside in conjunction with the 3" of ccSPF
Foam on top of the roof decking then the metal roof (thermal breaks..better way of doing it..but may cause issues for the metal roofing contractor)

Glad I've got time to figure this out..plus happy you guys are helping.

Why don't you get an HVAC guy to calculate the cooling load through your roof choice and then through the R19 insulation and see how many BTU's you're actually chasing at that point?

Your local building inspector may accept R19 instead of code required R30 based on performance values.  Usually, the spray foam MFR has a document of some sort that states that R19 of his product is just as good as R30 fiberglass.  Most inspectors accept that around where I live, it's probably the same where you live.  That doesn't mean it's the thing to do, just that it does get done that way.

IF the resulting cooling load through the roof is, say, 6000 BTU's on a design day, you might be better off to upgrade your air conditioner to a more efficient unit and add better windows or add additional shading or something rather than spend more money on insulation.

On the other hand, if the resulting load is 18000 BTU's, add more insulation.

tigerfan,

Nice suggestion.  I have a Calc's company doing th ecalcs soon..after final plans from architect.  Will see what they suggest.  Thanks to all and hopefully all will go well.