It took my transmission quite a while to get the shifts sorted out. Yes....it does defuel on each shift and that is what causes the delay or hesitation between shifts. When you want to "romp and stomp", some of the roughness can be cured by using tow/haul, which will keep the converter locked up. I know you want to maximize performance, but personally on my truck, I think WOT runs from a dead stop are smoother in #1 or #2. Also when making these runs, start out with only 3/4 throttle until the truck really gets rolling, then "bury it." I rarely use #3. Also remember that you don't reach the full fueling potential until the coolant temp gets above about 180 degrees.
2005 Chevy 2500HD, CC, SB, 4X4, Duramax, ARE Topper, 60 gallon RDS toolbox/tank combo, Kennedy Headlight Booster, Isspro pyrometer and boost gauges, EGR Blocker, PCV Kit, Bilsteins, 265 Michelin MS-2, TTS Exhaust, pulling 35' Jayco travel trailer.