Hi Lucio!
Talking on Plex 7.2, as it seems to be your version, we upgraded several months ago, without important issues. We have maybe thounsads of winc functions, and there was not problem maintaining 6.1 dlls with the new runtime. Simply we compiled with 7.2 any changed or new function, integrating them into the 6.1 majority of objects. Some of our found problems (winc):
In some scenarios, generating with debug option activated produced a GPF. It was solved with a fix. Same for an issue with grids, with the select grid subroutine: it was triggered again after reload grid (solved). There is a pending case with client calls to System i objects: call status is not returning error if a function/object is not found or fails.
There are a couple of minor issues for System i or java, but maybe it is out of your scope.
Jorge