I got a chance to listen to the new BX5a's at Guitar Center yesterday.
Now I've only heard the BX8's so I don't really know about the BX5's, but I thought the BX5a's were very smooth and detailed. They may be a little overly bright, as they were brighter than KRK v4's, v6's, rokkit's, Mackie 624's, and
Dynaudio BM5's. However, they weren't harsh at all, although that might have been the music they had. Unfortunately, they were wired out of phase and I was unable to hear any imaging, but I imagine it would be very good like the BX8's.
As I imagine the BX5's would be, the BX5a's lacked in the bass and midbass department. Compared to every other monitor, they had very little "oomph". Like many people say about the BX5's, I couldn't see using this guy as my main monitor without a subwoofer. As a nearfield, though, it would be a perfect check for imaging.
I really dug them. If you look at their website, you'll see the tweeter shape of these guys is really flat, don't really know what that does, but it reminds me of a JL audio car tweeter because of the rubber surround. I may go back and try to A/B it with the older BX5's to get a better comparison, but I really like these guys. I'll probably end up with a pair, but I'd have to look at subwoofers as well.