PSB or stick with vintage ADS

Agree with Frogman, don't be fooled by advertising hype. You indicated you could get an in-home audition, that is the best way to go if you'd like to see what the PSBs have to offer.

Interesting... 15 years ago I listened to many speakers that I felt could best my trusty ADS's. I finally found the PSB Stratus Golds kicked everything to a whole new level. Obviously this was many years ago, but from a value perspective, PSB is still a way to go. I had been an ADS proponent since 1978.
Since you're looking at used, the Stratus Mini is probably available at a great price. I know you said space constraints are a consideration, but if that is temporary, the Stratus Silver, Bronze, or Gold can be had at great prices, most likely.
I still wish I had held on to my various ADS speakers- they certainly were special... Good luck.

Well, I brought the PSB Alpha B1s home this evening, and I'm playing them now. Without getting into sonic detail, my "bottom-line, first impression" summary is this: They sound like they are a little smaller with similar quality, and, well, that's what they are. Ha. They sound about as good as I would expect smaller, less expensive ADS speakers to sound (different, but as good). So I wouldn't consider it a lateral move, but still a good move for downsizing.

They do sound better than I expected, notwithstanding all of the good reviews and my curiosity. I wasn't expecting quite the presence of the bass that they have (I do run a sub, so perhaps it's not as noticeable). It's not quite as tight (probably for being ported), and they don't seem to push quite the same volume before breaking down. But in this small room they don't sound anemic in the low end.

I generally listen with the tone defeat on (that's just a personal requirement I have for speakers, that they sound good enough on their own). The sound isn't quite as full or bright as the ADS, but they seem to produce more tonal accuracy in the mid-range, with more subtle, yet very clear highs. So they have more of a warm sound with a little less overall presence. An overall very pleasing sound that I could live with, I think. The size is really perfect.

That said, I have 4 days to decide, and the speakers have not been broken in as yet.

Whoa! Ok, I already have to update my last post. I had originally placed the Alphas in my entertainment center area (over the fireplace). That means they were sitting in an enclosed area, as if on a bookshelf. So I broke out my speaker stands and did a little rearranging in order to place them more ideally at ear level, away from the wall a bit, etc. And the sound really popped! I can't believe the difference. I believe I can honestly say I enjoy the sound of these better on the stands than the ADS, but the ADS sound quality wasn't as diminished in the entertainment center. Probably again this is due to the ported design of the cabinet, along with having them directly at ear level now.