I LOVE the SB3s. I really, really did NOT like the 3.1 predecessor. The SB3s are an entirely different speaker. I have listened to them at Tweeter and at a friend's house and never thought the bass sounded boomy at all. In fact, I think they come pretty darn close to the RB-5s! If you check the archives on the BB, though perhaps in a different forum, you'll see an earlier rave by me about this speaker.
Let me make a confession:
For my main, living room system, I still have the KLF20s, C-7s and S-6s, driven by a five channel rotel power amp and Sherwood Newcastle pre/pro. I love this system for music and for movies (primarily music), using a Sony S7700 DVD player for DVDs and CDs and a Rega Planar 3 for LPs and a Nakamichi tape deck for fun.
But in my bedroom, I have a, *gasp*, "high end" non-Klipsch set-up (if you check the archives you'll see I was struggling with this decision a while ago -- I've been reluctant to report what I bought). Anyway, my bedroom system is a Rotel RCD971 CDP, NAD 533 TT with Creek phonostage, Nakamichi tape deck (er, yes, I have two), running through a Krell KAV300i integrated amp, which is driving B&WCDMSEs. Expensive, but fun, and I really do like the way it sounds (that little Krell monster makes the B&Ws explosively dynamic -- really, you'll have to believe me). But, as I already said, this is an expensive system!
So, the point of my confession is that a good friend of mine bought as his main system an NAD C740 receiver, NAD C540 CDP driving a pair of Klipsch SB3s. It sounds AWESOME, WONDERFUL, MUSICAL AND DYNAMIC. It cost him about one third of what I paid for my amp, cdp and speakers. For me this is a fun hobby, and the market has been good for me over the past few years, and I like the Klipsch system in one room and Krell/B&W system in the other. They both sound great. But if you want an amazing pair of bargain speakers, get the SB3s. You cannot lose. They remind me in a way of the KLH and Advent speakers of the 1970s, NOT because they sound at all alike, but because they are so much better than the should be for the price. I had a similar reaction to the Cambridge Soundworks Model 6s, which are an old fashioned accoustic suspension design two-way bookshelf for under $300 these days. But the little Klipsch stomps it. A gem.
Now, if you have more $$$, I would go for the RB-5s, which I love even more and which are also a bargain. If you have even a bit more $$$ and quite a bit of room, go for the KLF20s, which are still one of my favorite speakers out there. I'm keeping mine until the new high end series of Klipsch speaker comes out (soon, I hope, eh Bob?). But if you are on a budget and short on space . . . well I've made my point enough already!