Ok, so I am building with open web 4X2 floor trusses(16") @ 19.2 O.C..  I had originally been thinking about batt insulation in the bays but am wondering if it might not be better to use a blown in insulation?

My original plan was to use 19" batt which will be compressed to 15.5 where the webs are located and expand into the areas between webs to contact(nearly) the insulation in the adjoining bays.

After seeing some horizontal blown insulation, I am wondering if the blown-in, being able to flow in and around the webs, might be a better way to insulate this floor structure.

Any thoughts welcome...

absolutely. batts will leave voids.

i am not a builder, but I would only ever use batts in something like a detached garage or similar (assuming it's cheaper), never in my main living area. blown cellulose should give you a good return and will likely be much cheaper than spray foam.