On our layouts server, which has been based off of p-g-qvm and Lakitu7's QVM, we have an issue with dretches walking. The best example is in this video:
http://knightsofreason.net/~aaron/downloads/dretchwallwalkhax.ogvWhich shows the issue when wallcrawling, but doesn't exactly show how bumpy it is when walking due to the low fps. The server also hosts a Tremfusion mod, KoRx. This bug only appears on THIS server, if you run the QVM locally, it doesn't happen.
I'm assuming it's an issue with a cvar, has anyone else experienced this?