When I play on DM servers, I usually use a high-quality config. Sure, if the server doesn't have fbskins enabled and lots of players use gray skins, its sometimes hard to see the opponents. I probably wont frag that fast anymore, but so what? Its DM, to a certain degree its always luck-based (if the good players keep spawning near to you instead of easy to frag n00bs
) and winning there shouldn't really matter too much. At least for me, DM is about action, cool frags and having a nice chillout.
1on1 is a different story though. I still have geometry and texture quality on max, but got most lighting settings (lightmaps, bloom, hdr..) disabled. Together with fbskins which are usually enabled on minsta 1on1 servers, I have a perfect sight. Don't really see the advantage of r_showsurfaces 3 or something there. But I only use settings which are in menu (beside of r_sky 0 ok..), so if those settings are in menu, they are supposed to be customized, or not?
If you don't want this sort of customizations, you could be better of with buying a console. All PC games I know about are somehow tweakable, not only the open source ones.
Anyway, in my personal experience you can have lots of fun, good action and be quite competitive in DM games with a high-quality config.
The only thing I'm pissed off is because of that build-in "wallhack". Ok, map makers may need it, but isn't it somehow possible to disable those cvars server-wide?