...entirely up to you whether you accept my counsell or not...
Yep.
This is new information about your ATC100 experience. In what context? The reason I ask is that two of the worst dealer demos I've experienced involved ATC active 50s and 100s. The supplied stands don't do them many favours.
Two independent listeners have expressed reservations about your system
Yes, but look who they are. One had made his mind up before he arrived, the other is -ah- rather, um, eccentric in his tastes, perhaps? In any case, my system exists to please me and Kathie, and not necessarily anybody else. If other people like it, fair enough, if they don't, well that's OK too.
OTOH, I have heard Isobariks in many different domestic settings, for long periods. I can see the attraction, and I actually quite like them, up to a point, but they are nowhere near as good as the ATCs in my opinion. Isobariks are very, very cheap to buy, and if I wanted a pair, well, I'd buy them.