You posted the same question in the Leica forum, right? No problem, I'll respond here.
I never considered the Tri-Elmar. The fun of shooting rangefinders is in the fast lenses most use (and in this context, even a f2.5 is fast next to the most popular zoom, which can easily be a f3.5/4, or worse yet, f4/5.6). A lens like this, to me, defeats the purpose of the rangefinder, or at least the reason I like them, by forcing me to use slower shutterspeeds before I want to, or faster than usual film.
What's the minimum aperture of the Konica reply to the Tri-Elmar?
In any event, the best thing to do is have a couple of bodies with different primes. But then, that's me. In sum, the premise in your question (that this lens doesn't perform as well as its prime counterparts) remains to be seen, but one can tell it's not everyone's favorite.