My observation: for M lenses, standard and tele generally work fine on m4/3. 28mm or shorter, you start to see significant drop in image quality, esp. at the edges. (35mm is probably at the border line.) Most WA RF lenses show "smear" image at corners. One good example is the ZM 25mm. Great WA lens on films, but performs poorly on m43. Likewise for Leica 28mm f2 and f2.8 ASPH. [These WA lenses work just fine on digital M though. I believe this has something to do with the different sensors' orientation of these two systems.]
So, m43 is great for short tele, no so for standard nor WA. (One would need a great 25mm f1 lens to get an equivalent 50mm f2 lens on m43, so even the super-expensive Leica 24mm/1.4 summilux is not enough.)
milaurie