Snell AIIIi's?? How good are they??

Yes, I would say the AIIIi’s are that good. To this day, one of my favorite sounds heard from a dynamic speaker; not that I’ve heard all, but have heard many of the contenders from that era. Ever since hearing a pair driven by VTL monos at the old Sound by Singer I have lusted after a pair. Not the kind of “electrostatic-like....for a box” sound that many more modern dynamic speakers seem to go for these days (with limited success, IMO), but detailed in a natural way, dynamic, beautifully full mids, great bass and image density; and that hard to describe ability to let one sink into the music and not worry about about those very things. Wide and stable imaging, if not the best front to back. Twice I have considered buying a used pair, but both pair would have needed woofer reconing and I got cold feet. Make sure that you inspect the woofer cones before buying. Personally, if in great shape, I would pay up to $2K for a nice pair. Good luck.

They are as good as they were 27 years ago. Speaker design has changed considerably with the aid computers in the last 20 years. Today’s speakers are much quicker ( faster ) than speakers from just 20 years ago. Lighter, stronger materials and like I said computers have all made speakers better than anything from the 90’s.
As for the Snells, I owned almost all the E and C series in the 90’s.
Very flat, un-colored  sounding speakers. They sounded great with the right equipment, but put anything bright or harsh behind them ouch. That means recordings too.