All else being equal....

[ul][*] Thinner is faster but thinner also stalls sooner[*] The more forward the max thickness (within reason) the more delayed the stall. Further back stalls easier[*] Camber in the airfoil raises the max lift coefficient you can achieve before stall occurs
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In looking over Profili I found that there is an Eppler 472 that is 12% with the high point at 17.5%. That may be a good compromise. It'll tend to delay the stall and thus avoid high speed snaps in tight loops and turns but should be thin enough to let the model fly fast. The gain in lowering drag you would get by going to an airfoil with the max thickness further back than 25% would be offset much more by the reduction in stall resistance IMHO.

Don't forget light weight is also important. Lighter models loose less speed in turns and also accelerate faster out of the turns.

Scale combat models use 25's on models as small as 36 inchs. That's why I was wondering why you spec'd 72 inches for the .32. I would suggest that something in the 48 inch span with about 400 to 450 sq inches would be fine. The wing loading will allow fast turns and good acceleration if you can keep the weight down to about 2.5 to 3 lbs.

I'll also repeat that if you find that more of your combat flying so far involved pulling positive G than pushing negative G then you're a prime cadidate for an airfoil with a bit of camber (think semi symetrical here). The gains in delaying the stall during positive G may easily offset the loss in negative G turns. Just set the elevator travel limits so you don't get as much down elevator as up. You should have the elevator throws set such that the model does not try to force the airfoil past it's best Angle of Attack in any event. If pulling full elevator at medium speeds makes the model over rotate and forces the model into a tight but slow loop then you've got too much elevator throw.