What I look for is tonal accuracy, open and clear midrange and dynamics, as I feel these are the most important parameters that can give you impression of live sound, in other words a reproduced sound of live unamplified instrument is as real as possible, in all harmonic richness.
Given your described tastes, I can only suggest a bigger PMC or ATC - the midrange on the ATC 100's uses ATC's much bigger dome midrange drive motor (PMC mid dome is similar to the smaller ATC 50 in drive motor size, PMC like Proac used ATC drivers in the past).
The ATC 100's might be too forward for your taste and the bass might be too lean and punchy compared to the PMC TL design but you should at least audition them. ATC's also run class A to 2/3 power with three separate amplifiers (one for each driver - true active speakers) unlike the PMC IB2 Active which has a modified 4B-ST single channel amp on each speaker (great amp though - I also own one of these). Anyway the ATC may give you the extra edge you are looking for....however, quite frankly why bother - the current speaker you have is already EXCELLENT! (If you go ATC then definitely go active. With PMC it is not as important)