Originally posted by maciek_w the 43 is my primary lens. I use it for about 75-80% of all my shots (partly because I have nothing shorter, and partly because it's the most practical of my lenses - the DA 70 has too long FL to be a comfortable all rounder)
So, I'd ask myself:
do I want something shorter?
do I need the extra speed for general use, or particular uses (e.g., portraits)?
would I miss the 43 if I sold it, or can I justify keeping it along with another costly lens?
The * 55 is an excellent lens no doubt, and particularly for portraiture. But just possibly you'd be better served by something shorter, maybe the 31 (which is scarcely faster than the 43) or the Sigma 30, and buying a cheaper but optically excellent MF lens for portraits (any number of good choices here). I just offer that as a suggestion, as this is obviously a matter of personal preference.
Just to stay on topic
another cross post, shot today (as was the Robin, above):
DA * 200 @ f/4, cropped a bit