I have both BL 11 and BL 2 in my set up and there is just no comparison. I have also owned a variety of other subs. The BL 2 is totally in another category when it comes to performance compared to the BL 11. The BL 2 is one of my favorite subs out there from any brand - I even prefer it to the BL 19.
I know some mentioned the Cambridge Audio Minx X201. Interestingly, I have post here somewhere where I replaced my BL 11 at one point with a single Minx 201 and once I had adjusted the settings the tiny Minx X201 outperformed the BL 11. If you get two Minx X201s, remove the grills and connect them together (the Minx has an audio out connection to link multiple subs) you end up with an aesthetic that would work well with your BL 3 and you'd get performance that would blow away the BL 11 - by a long shot. Yes, I have the BL 11 in my set up only because of how great it looks, if I wanted better sound, I'd get any other sub in a heartbeat.
My 2 cents worth. FWIW, I find the combo of BL 2 with either BL 8000/8002 or BL 3 to be a perfect match. They sound amazing to me. BL 2s are quite cheap right now, I have no idea why, but in the US they are 50% cheaper than a BL 11 (I guess form over function has a lot of value)
I completely agree. I thought the BL3s sounded great for their size. When I added a BL2 to them, I was amazed at how the BL2 elevated them to an all new level. The improvement that a BL11 adds is very subtle.