Funny, all this thread is doing is me wanting to try out the Summaron on the 240. RFF is evil.
Roland.
it's really a great lens.
I hear lots of people say it's just not good for color, has mediocre contrast, isnt suitable for modern "real" photograph or other somewhat ridiculous things, but to me, it's the epitome of an excellent RF lens. (especially with the infinity lock removed) I've also not experienced any of the issues others claim.
Every once in a while I get tempted by some other 35, recently it was the new 1.7 ultron, but they just dont look as pleasing to me as the summaron or offer the same incredibly small\light\no vf blockage\fit in a coat pocket (even with an m240) that it does. Basically for me, it turns my m240 into sort of an x100. To me both of the lenses share a bit of character, minus the haze of the 23mm at close focal distances and big apertures. I also find the summaron\m240 combo a good bit sharper.
either way, sorry for the semi-derail of this thread.
If the summaron is not fast enough for the OP, neither will the summarit/f2.5 that was originally listed as an option. The summicron suggestions seem to be well suited for a little faster. Next I'd look at the Ultron I mentioned above if a more modern rendering is preferred and you really need the speed.
Since it does sound like cost is an issue, rather than the Lux, FLE, summicron, or even new ultron (surprisingly expensive), i might list the Nokton 1.4 MC as a third option. I've seen many excellent deals on them lately, with the hoods included. Sure, it has some distortion, isnt the sharpest (but is sharp enough imo), and compares favorably I find to the other Lux 35's. Since ultimate sharpness and such doesnt sound like that is too important for the OP in a 35mm lens, the Nokton 1.4 is a great handling, a bit classic, small, modern coated, lens that wont break the bank or block too much of the VF and could work reasonably well as the only 35mm so long as you're not afraid to shoot stopped down or are concerned with dead flat\straight lines.
edit: and while I have no first or even third hand experience with the lens, I feel like this is the point in the discussion of 35mm lenses where someone mentions the 40mm summicron. (edit2: and I see someone already suggested it in post #6)