Virgil, good to see you chime in on the subject! Excellent post....which is a great addition to the many other excellent posts preceding it.
I've been mulling this over, both in an effort to remember when I've encountered sonic issues, and ultimately in hopes of eliminating them. In my case, the common variable, aside from "difficult" rooms, seems to overall volume. When the band is cookin', the issue is at worst mitigated and at best simply gone. However, at lower volumes it can become downright frustrating. FWIW, on most of my gigs I'm not reinforced, so the rig represents the sound of the bass for the stage as well as the entire room. I've yet to encounter any problems in larger rooms where there is reinforcement.
Ken, for better or worse, I believe you're correct - neither the 502 or 902 are leaving music stores in large numbers. My local shop - bass nirvana for the SF bay area - has one of each that have been sitting at blowout prices for months. And on a deja' vu type of tangent, I'm getting the same response from TecAmp (or at least the U.S. distributor) that I got from Epifani when I was originally in the market. Nada, zilch, niente, nothing.
Nonetheless, I wouldn't say the point is moot. There are a number of us who are heavily invested in finding the "right" sound, coupled with durability, flexibility, and any number of other considerations...i.e. weight & portability. It's great discussion in threads like this that are really helpful for everyone in that category. So - thanks to all for sharing your real world experiences!