Hello Robert,
true, performance is superior using Crossover vs. vanilla Wine and POL.
It's about 7:00 am in the morning here and my gf stopped playing Draenor about two hours ago. She played about five to six hours of WoW Draenor straight - via Crossover, without a single crash. I'll ask her to make some screenshots of her journey later tonight, but for now I can provide the following feedback:
Ubuntu 14.04.1 64-bit is our primary stable OS (we also have 14.10 around, but that's only for testing as it can be extremly unstable sometimes, LTS is the way to go)
AMD Phenom II X4 @3 GHZ
AMD HD 7850 1GB GDDR5
8 GB GDDR3 Corsair RAM
Settings: 1080p resolution, Vsync OFF, FXAA activated, good/fair details selected in WoW, performance enhanced graphics ON, D3D mode activated, new character models activated.
The game runs decently with relatively high framerates @ 30-100 fps /depending on the situation etc. but we limit it to 40 fps in order to avoide headaches. I haven't tested 25man raiding yet though, but I am looking forward to that in the next 72 hours. Anyway, there were no major issues whatsoever, only a single but extreme framerate dip to 5 fps, which stayed like that for about half a minute when she was in a group of five doing the Blackrock dungeon. After a few seconds, fps-rates were up to normal again.
Usually we'd be using the Open Source Radeon drivers that Ubuntu provides at default, but this time around we were forced to use the proprietary default AMD Catalyst drivers provided by Ubuntu. Performance with the Open Source drivers is good and much more stable, system integration with Unity is superior and smoother too, but there is a bug with them in Ubuntu 14.04.1 64-bit. The bug is caused by a buggy LLVM and Mesa driver combination, which has yet to be fixed on this release of Ubuntu. This issue causes a lot of games to crash when using a specific combination of graphic-settings in games powered by Wine/Crossover and it also happens in games played natively - including WoW. This issue has been adressed + fixed in Ubuntu 14.10 64-bit, which ships with a new graphics stack + Mesa drivers, but performance took a major hit. I'll provide more details on this later.
I have yet to experience an OOM error. If you could tell me where your char was when the error occured, I'd be willing to test it later. :)
Cheers,
Alex