Some initial thoughts on these options:
OPTION A:
Pros: Pure philosophy, no question of getting the single driver magic
Cons: Such a driver is almost impossible to find. MUCHO dinero must be spent to even come close, and some may argue that trying to cover the ENTRE spectrum NECESSARILY leads to compromises in reproduction capability. The best drivers like AER may still not be as good, for example at 15,000 HZ plus as even average tweeters.

OPTION B:
Pros: Cheaper solution. If a sufficiently wide range is identified (say 50 HZ till 12,000 HZ) then purity compromise may be less. The best drivers that reporoduce a limited frequency range may be BETTEr than the best drivers that reproduce the COMPLETE range. For example, it may make sense to get a really widerange driver, and get tweeters and a biamped subwoofer for the really extreme frequencies.
Cons: Lack of purity and philosophical compromise.

I can tell you from my personal listening that option b TO ME really offers no compromise in sonic purity (at least to my ears) as along as a sifficiently wide range is selected. But then I am a cheap b____ with not too much money to burn on drivers.

Thoughts by others are welcome! I know we have discussed this before, but this seems to be the fundamnetal philospohical question that we seem to come back to in our single driver world!

-akhilesh