[pbp1]

Sequential injector operation offers the most precise fueling. That being said, as injector duty cycle increases (meaning the injectors move closer to just being wide open), the difference between bank to bank operation and sequential operation diminishes. Now, selecting a large injector that will operate at a lower duty cycle gives you the room to "time" the injector open time in relation to the opening and closing of the intake valve. Operating in sequential mode also gives you the ability to add or subtract fuel to or from individual cylinders to find an optimum balance of Air/Fuel ratios from cyll. to cyll.
Now these are very small potential gains and there are no hard, fast rules to go by. If you have unlimited time and are willing to spend the time on the dyno testing every possible combination of injector size, injector opening timing, and individual cylinder corrections (and the XFI 2.0 system allows all of this) then I am certain you could find some power.
That being said, I have seen racers run their systems in bank to bank with great consistency and run in the 1.25 under range any time they want.
I guess the short answer is that it is likely that you can find some power gains by switching from bank to bank to sequential but there is no guarantee that the gains will be worth the investment required to properly test to find the optimum parameters.
I have not seen any evidence that sequential fueling offers any more consistency over bank to bank.
Now, sequential definitely offers better idling, drive ability, and part throttle operation so if I were running a stocker, it would definitely be in sequential mode.