I have got today a couple of Kipon adapters and I made same quick test shot with the most difficult RF lens I have, the CV 15.
One good news is that I have not detected any substantial color shift, the bad news is that the borders and the corners are substantially mushed: I made a comparison with the same lens on the Ricoh GXR, and in this regard the latter is substantially better.
A second bad news, not related to this WA lens but more general, is that the manual focusing is hardly usable also with the legacy lenses.
As long as you can live without magnification it may be fine but the enlarged image is very unstable and as such totally unusable for the fine tuning of the focus.
And of course there is no focus peaking.
Hopefully the handling of the manual focussing issues can be addressed in a future FW, the bad performances in the edges and in the corners I am afraid are strictly related to the sensor design (absence of microlenses?) and so much more difficult to improve.
I did not buy this excellent camera to use it with legacy lenses, so there is no regret on my side, but since I have excellent M lenses I just wanted to try.
The second adapter I got is for Nikon mount lenses and I will use it to see the performances os same Leica R I have on Leitax mount.