The Banks flywheel has not yet been released. So it is not an option at this point. I have never seen the Opie version, however as with everything Opie does, I'm sure it is very nice.
The ATS flywheel will work with any converter. I have one in my daily driver with a 1057 converter. You need a .160 longer bolt to make up for the difference in thickness.
I just weighed a bunch of stuff for you guys. I think I did this once before in a different thread, but here is today' results.
LB7/LLY flywheel assembly: 19.30 lbs
LBZ/LMM flywheel assembly: 20.75 lbs
ATS flywheel assembly: 18.10 lbs (Yep, lighter than the other two)
Last I checked the ATS is a one size fits all, however LB7 and LBZ have different counterweights as illustrated by the data posted above. Bottom line, I wouldn't install one unless I had it balanced with my crank assembly.
IMHO, the stock converter with it's sheet metal cover has bolt pads that vary in height. The stock flywheel assembly makes up for this with it's sheet metal connector, hence the flex is needed to make up for the production tolerances of the stock converter.
Triple converters with billet back covers are much more accurate with regard to heights, hence the flex in my opinion is not needed.
Hope this helps,
Guy