Interesting. I never thought of Mozart as aggressive but hey what do I know.
Hehe, maybe Mozart was the wrong reference
What I meant was an A and E (specially E) that is both fast and fat in sound for "rapido" music. I agree with you that the BC´s blend extremely well with the rest of the section.
For me it is also ipmortant to have a set that works very well with pizz playing, and sound beautiful under the bow. Mixing BC and Spiros solves that problem I think. The Spiro E and A sounds cool under the bow, the D and G too nasal and harsh. The Spiro D and G also is too bright pizz in my opinion. The BC D and G had the sound I was kind of missing: organic pizz sound and beautiful arco sound. The A is kind of OK, the biggest problem is the E. I´ve got a wolf with the BC A-string, and thought maybe a Spiro A would be better and perhaps tame the wolf.....