I personally think it depends whether you will use a 5.1 or 7.1 setup. For 5.1 I'd invest in some BL3s, but with 7.1 the sound is entirely surrounding you and the BL5s will puff out enough heavy sound so the BL6000s shouldn't have to struggle with anything.

Design wise, I love the BL3s and BL6000s enormously, but the BL3s will probably best suit the BL5 design.

As repeated by us all in almost every thread, you should hear them yourself and better still in your home. You'll make the right decission then.

As people here know I have some pretty set opinions on rear speakers in surround. So I won't go into those. (Phew!)

But after Peter disclosed that the BL6000 come with a wall mount (see News here) I have been wondering about using these instead of BL4000s for my surround. As far as performance goes they're quite comparable in output, but I'm intrigued by the opportunity to have these sleek speakers providing my surround.

AND - I have this weird notion that I'm going to be placing them horizontally, not vertically, on the walls. Rotated so that the drivers are pointing towards the main listening position for the music room/home theatre. Two in the back, and possibly another two - to either side if I decide to go for 7.1 (well, given that each BL5 has a subwoofer extreme, I guess that should be 7.2).

But I think they're going to look great like that - and do a solid job. 😎 

I am curious. 

The lower frequencies that are represented by the .1 are omni-directional aren't they. So theoretically, having .2 wouldn't result in the lower frequencies being separated into stereo, as the human ear would not be able to detect it.

As far as i can see, having .2 would simply result in a more even distribution of the sound.

Am i on the right track, or is that completely wrong?

soundproof:

Two in the back, and possibly another two - to either side if I decide to go for 7.1 (well, given that each BL5 has a subwoofer extreme, I guess that should be 7.2).

But I think they're going to look great like that - and do a solid job. 😎 

The problem with having only one sub woofer is the possibility of standing waves at low frequencies giving different positions where one gets more or less bass. Having  two reduces this effect.  Besides, it means they sell more speakers!

soundproof:

Two in the back, and possibly another two - to either side if I decide to go for 7.1 (well, given that each BL5 has a subwoofer extreme, I guess that should be 7.2).

But I think they're going to look great like that - and do a solid job. 😎 

Even distribution, yes. Though the BL5s do process the bass so that you can hear it is supporting things to the left or the right of the soundstage (or center, for that sake). And there are possibilities, with DSP, of tying the subwoofer to the midrange info - so you can then actually pan the bottom (at least it appears as if you are).