Thanks for the insight Dave! 540 was absolutely relentless with the magnets in when it wasn't being a bit smokey! HardWired, I'm tempted to use a similar concept with less downforce, I seem to recall 540 fighting NST and it bent one of the Hardox sides in because there was no where for that energy to dissipate to since it wouldn't budge!
I do have 7mm hardox on mine and there'll be some HDPE on there too to soften the impacts some more, there's a nice enough air gap around everything, so any dents in the chassis won't really disable the robot but obviously want to avoid it as much as possible! I'll probably just trial things out between now and next year, see how it all works and try to get the optimum level of downforce and speed. Ideally, I'd like the level of speed 540 had when the motors were in (high?) gear but naturally I don't want smokey motors either, even if I am trying something new out.

It's probably the best way to put the power down though! Perhaps 40kg might be a little too much for mine, but again - definitely something I'll try out!

What sort of size was 540 too if you don't mind me asking? Looking at it on there, it looks like it was a very compact machine! Also, how did it fare against flippers? I've never seen it get flipped, it looks invertible but I'd just wonder how it would have managed without the magnets working, and what effect it had on how far the flipper threw it...