My impression of B2: Yes, it reminded me of M4 (mostly mids). Then, I noticed it has very adequate amount of bass quantity, similar to HM5's. The bass is tight, punchy and fast, compared to my HM5. There's nothing much to write home about in the midrange; there's more authority in HM5's vocals and the mids are more "intimate" than the B2's in spite of HM5's much bigger soundstage and airyness. The highs are just the way many have described - aggressive and emphansized. Personally, I don't have any problems with that, and I also enjoy the sparkles very much. However, when I tried the frequency sweep, I couldn't believe the amount of energy there is in the 7-8kHz region. It was almost deafening such that I needed to turn the volume way down. The treble energy seems to keep increasing from around 3kHz and peaks at around 8kHz, then quickly rolls off thereafter. The treble can be problematic for some, when one uses B2 to watch movies or play games, because gunshots and explosions are overwhelming and edgy (realistic?).
In short, B2 is perfect for you if you love detail, don't mind treble and appreciate nice controlled bass. It is crisp and clear. I really like it.