I just got these, I was hesitating between these and Prodipe Ribbon 8 which I heard in a store. I finally went with Behringer for (don't laugh!) quality reasons and ...
I'm very happy I did
They sound quite neutral out of the box, stay balanced at very low or high volume, there is a lot of power reserve, you can definitely blast your ears if required. The soundstage is just a tad less detailed than Genelec 1031APM (which I know really well) but still quite good, dynamics seem similar with a focused low end (I think the more expensive originals are actually more flattering in the lows), in your face mids and treble (with almost no hype). To be honest I was expecting more brilliance from the ribbon tweeters and am pleasantly surprised at their more than decent behaviour.
The horizontal sweetspot is incredibly big, moving around is no longer an issue, no wonder Adam are so successful . Vertical directivity is quite strong however, place them at the right height!
Nice too: low self noise (hiss), no noticeable transformer hum, the OdB notch on the trim potentiometer, no port chuff that I could notice.
Out of the box the input trim is at -6dB, when I tried them initially I thought they were lacking lows, turns out that once the trim is set to 0dB, the lows appear ...
It seems to me that they play in a different league than the similar priced competition (Fostex PM2, Mackie MR8, KRK RP8) and I would not be scared to mix on these even if there are better much more expensive monitors, but in this price range, wow! Definately check these out if you don't have thousands to spend, and make sure input trim is flat as attenuation cleary changes the monitor's response.
On the side: I saw a lot of hype about these on home cinema forums, I actually wouldn't recommend them for that, a more hifi-ish sound (The Ribbon 8's for instance) would achieve better results.