I have never heard the BL12-2 but have plenty of BL3s. I would state the BL3s are 2003-5 tech, the 12s a little later. However, it is likely they are just different form factors of the same/similar thing. Although good, I think todays modern Labs will probably blow them away.  The BL11 will however lift both speakers in terms of tonal response. I think the question to ask is what are your labs used for (primary music, surround etc..) and how do they fit with your living and decor?    

Thanks for the response. I only use them for primary music, I often play records on my turntable through them. I enjoy the precision of the Sound and I enjoy listening to them at a higher volume. In my opinion the 12-2s sound great, especially for their size. But in comparison to other speakers, for instance the BeoLab 18s, they sound quite flat and hollow. I use them with a Marantz Pre-Amp with Audyssey Room Correction with wich they sound pretty good, however listening to them in normal mode with Room Calibration turned off, they sound pretty bad like described above. I was wondering if the Lab 3s had a more rounded sound to them, not being quite as flat sounding? Best Regards Thorben

I'd say the Lab 3's just about edge it - but don't expect huge sound from a wafer thin cabinet, or a very small cabinet.  The Lab 3's have more driver area (if you add the three up) but at the end of the day they're still small speakers so won't exactly rattle your teeth. If you want big sound from a small cabinet, look at BeoLab 17's.  Vastly underrated and very much overlooked. Lee