I have a 24mm Elmarit ASPH and M-P.
I'm not sure if I can describe it as contrasty, nor compare it to the 28mm f2.8 Elmarit which I don't have. Besides, I don't find any issue with contrasty lenses like the 35mm or 50mm modern Summiluxes as there's enough information in the DNG to recover the file using the contrast sliders.
But I do recall that the 24mm Elmarit is well balanced vs say the 35mm ASPH Summilux when I used them on film cameras. I would say the 24mm does pop. If you had a 35mm ASPH Summilux as a 10, and a uncoated Elmar from the 40s as a 1, I would call the 24mm Elmarit ASPH as a 7 or 8. I would describe the lens as very well balanced and flat on a M-P (or M240 which I believe is the same sensor).
In fact, the 24mm is one of my favorite lenses, performance-wise, but it doesn't get most of the mount-time mainly because of the need for an external viewfinder.
-bt [Leicanaut & Nikonaut]