Thank you all for your advice and comments.
As I mentioned, I asked my local dealer to demonstrate the BL3's with the sub BL2. Let me tell you that my selection for this test was classical music with strings and a lot of high and low passages. I'm not very fond of using subs for listening to music because in my experience they tend to add very artificial sound to the music getting it too "boomy" for my taste. I did not expect the pleasant surprise I got. The result was truly impressive, the BL3's were relieved of the burden of low frequencies and therefore were more relaxed and able to produce a detailed and rich sound without the "stress" that I reported earlier. On the other hand, the BL2 did not overhelm the sound and was more of a companion instead of a protagonist. The sub did not reproduce the usual boomy sound of traditional ones and the resulting sound was very natural, detailed, rich sound and an overall pleaseant experience. With this setup I got the chance to really appreciate the ALT and the soundstage it provides.
I performed the same test with the 4000's... to be honest I'm still impressed with these little devils. I still find the sound natural and the only word I've found to describe it is "organic": I could even hear the resonance of the soundboard of the violins. I think that they are an absolutely excellent option and a bargain for their price range.
I'm opting for the BL3's because I now understand the advantages of the ALT, because I truly enjoyed the details that they produced, and because I believe they have more future. I'm sure I'll have to spend more money on the BL2's to fully complement them. I chose the red ones to match my decor.
I'm not putting the 4000's out of the competition, I'm completely in love with their sound and value and I will surely add them to my system for other listening areas.
Again thank you for your advice and keep in touch
Mike