I had normal SL's. Couldn't drive into the highback cause it just twists and folds. Landed on my jibstick and stayed there till I sold them, and now they're on a Nitro Subzero. Which the kid likes them there. So yeah, good park binding on a super soft jibstick...
If you're really willing to drop the money I doubt you'll really find anything more responsive than Diodes. Very slim chance Flux DMCC's might be, might. El Hefe's are probably going to be the more beefy of the three, maybe able to take a beating better.
That doesn't make any sense. I have a buddy that has an Atlas on a Heritage and I put in on my SL. We don't have any problems with heelside initiation at all. Did you rotate your highbacks? They flex laterally, but are very stiff longitudinally.
The SL's have a very similar highback.