I just tried an OSMC build (because the version of LibreElec I tried first had no emulators preinstalled and I wasn't able to figure out how to get them) with Retroplayer because a few nights ago I also tested the Android and Windows builds.
OSMC has some Libretro Cores and I only tried SNES yet. But Beetle bsnes and bsnes-mercury crashed right away (Same for ScummVM by the way). I only tried Super Metroid and NBA Jam TE on Snes9x and Metroid had some serious slow downs starting during the Intro. NBA Jam had some minor graphic issues.
At first I also had some controller issues (wrong mappings) but I can't tell if I fixed that by setting the driver to udev or by manually installing the SNES controller profiles from the windows build (seems like the Kodi Addon Repo is broken on the OSMC build. I wasn't able to install anything from it.)
Otherwise I have nothing major to say yet. It still has no support for Metadata/Images yet, so currently there is just the default lists available.

I can't wait to see how well it will perform in the feature.

Edit: Deleting the Addons27.db file from the userdata folder solved the download issues from the Repo.