For 4X5 photography I occasionally resort to hand-held press style photography. In low light I have been pleased with HP5 rated at 1600 and developed in Microphen. Unfortunately regular 400 speed Tri-X is not available in sheet film. How well does its cousin, Tri-X sheet film (TXP 320), react to pushing? Would Diafine be the way to go with TXP? What useable speed do you acheive with Diafine? The 'massive development chart ' suggests rating TXP @ 1000 to 1200.