I'm not sure if we're on a different page about the 'limit' or not here Adam, and you're the race driver so I'll concede all day long. Just to clarify my point in the mean time though, I've felt the same sensation in a Mk1 Fiesta at its 'limit' as I have in a V8 Vantage at its 'limit'. Loss of grip feels the same no matter what speed you're doing, in my experience.
Again though, I concede that you have way more experience on track, so I know nothing!