I do have BL3 in my main room (~35sqm) and BL6000 in my office room (~12sqm) next to the main room.
I was choosing the BL3 over BL4000 at time I bought them as the sound is much clearer. I also do not feel that any Bass is missing. They are simply very good and I am usually listening not too loud.
Then I bought the BL6000 from Lifestyle Av because I did not want to spend lot of money on mew speakers. For the office they are just wonderful. For the main room they (alone) would not be sufficient I think. Some weeks ago I was listening BL4000 with and without BL11 (Dealer has a testwall for easy switch on/off the BL11). The difference is amazing!!
To summarize: I think the BL3 make a much clearer (more technical?) soundstage. Think this comes from the acustic lenses. The BL6000 are warmer, but suffer from Bass and are not so clear. With a BL11 you can solve the Bass issue. If you prefer the warmer or clearer sound is up to you.
Heribert
BeoVision 8-40 / BeoVision 8-32 / Beovision 6-26 / BeoSound 3200 / BeoSound 1 / BeoLab 3 / Beolab 6000 / Beolab 2000 / Beoport / Beomedia 1 / 3* Beo4 /BeoCom 5 with VOIP