Can someone explain the difference between band on and band off vb's? And wich one is better?

I believe your referring to the LBA(low band apply)
valve body... if the band is on it will help protect
the over running clutch... easy to find out if you
have it... decell in manual low... if the engine slows
the car its a LBA.. if the engine free wheels in low
its not a LBA

The original manual valve bodies didn't use a band apply because timing the 1-2 shift was cleaner with just applying the kickdown band. Older valve bodies were just modified stock ones so timing the release of the rear band and application of the kickdown band was somewhat problematic.

Valve bodies have come a long way since then so the low/rear band apply valvebodies are very nearly equal to the valvebodies without the LBA plus they do offer additional protection for the over running clutch which is argueably the weak link in the Torque Flight.

I c i c!! So if one was going to have a 727 built to withstand 1100 plus hp who or what would you use? I know a pg would be easier but i'd like to stay mopar.

For that power/torque level, I would recommend a 16 roller sprag to replace the factory 12 roller one. Both the A&A Ultimate Sprag and the Coan Super Sprag are good.

I was on coan's website i think i'll just buy a complete unit. I think it'll make my life a lot easier