[Obioban]

Slides are absolutely the greatest failure point. We use the same slide provider as Recaro, and have redundant fail safes to keep the seat attached to the car as they fail 100% of the time in pull testing (which, unless you're running a seat back support, is what you do any time you go into a wall backwards). We have tested the slide provider than Sparco uses, and they're significantly weaker. For my personal cars, I'd only use the slides that BMW provides (as they're designed to take belt loads or reverse crash loads), or bolt the seat directly to the floor (which lets you properly locate the belts, which you can't do for any position but one with slides).

VAC seat mounts:
Their underlying issue is being slotted front AND rear where the seat attaches (meaning only friction hold it in place, so it can built up inertia in a crash-- only one side should be slotted, so the seat can't move), and not enough material between slots. Every other seat mount maker I can think of only slots one end of the mount (which should be the front, as they take less load on average).

Using my best MS paint skills, first his seat failed at orange, then it failed at red: