Well most games will not run as good on the open source drivers, ESPECIALLY Nvidia drivers, at this point in time. I am also weary of having some random, forked Mesa lib floating around my system, as literally, as soon as I update my graphics stack, I have to go back and copy it back in.
I have read that article, and while it can be a performance boost, the fact that you would need Mesa from that git to be installed, which would need sudo, so we wouldn't be able to do that in a script, either.
Now, the Wine devs are working on getting it, but have not fully pushed it forward for various reasons. Again, I could imagine that you need a patched, out-of-tree Mesa lib.
That repository is also pretty dead. Mesa and Wine have both gone through major updates in the last couple of months, and unfortunately, this repo is not keeping up.
Can you run some benchmarks WITHOUT the patched Mesa lib? Or is it required for the d3d9 patched Wine? If it required, then it is something that would probably need to wait until Mesa and Wine have that feature publically available. If you can run it WITHOUT the patched Mesa, I don't see why we couldn't try out a build of it.