So, to recap:
It costs about the same to keep the 272+250DR and buy the SCM40 or to sell the 250DR and get the 272+40A. Both alternatives have their pluses and minuses but SQ wise, which one is better?
Starting at which NAP level do the passive 40s sound better than active 40s? 300? 500?
If ATC offered an active version of a particular model i was interested in then to me, it would be a compromise sticking a passive crossover back into the mix. You really need to find that out for yourself though and see which route you prefer.
Technically better doesn't always translate into musically better.