I played Ren Calssic, Ren 4.0, Ren 6.0 (though it was not as good as classic) and a little ren 5.0 (which was kinda goofy) and TAC.
Mods that I checked out but never got into were;
insomniax (which I was totally confused by)
UltraRenegades (which was boring)
Annihilation (my computer sucked to bad to keep that much stuff going... similar things happened with later versions of shifter)
Shifter all up to-X (didn't play X for more than a few minutes)
Delta Force
Chivalry
mech2
happymod
meltdown
sex
bluesex
meltdown hell (it had it's high points, but the warp-pack (?) people made it no fun)
hybrid
...and probably a multitude of others that no longer exist.
Concearning rpg mods, I did a fair bit in each of the following;
Red Dwarf
Old World
Minotaur Outback Steak House
Ozzy's version
PK Palace
Uber Bar and Grill
Forests of Hyrule
PCRPG
Asylum
TvT (all 3 of the first public servers)
Divine Mythical Realms
MR
Forests of Hyrule MR
...and probably a number of other servers just to test them out (like Land of Friday/Friday's Mod, for example.)
and where has it been proven?
Well, I agree with UG on this one. I had been a base and shifter player with out a clan for at least 2 weeks before I joined a clan in Renegades Classic. I had been scouted from a Base server and asked to play in the Ren Classic server for tryouts. I made it (though it was my second week, and the clan was on the top 20 at the time when OGL had the most active tribes teams) and started to play renegades all the time. I became really good at capturing the flag, but my dueling skill that got me in to the clan flunked out on me after a few months. Renegades was about running away the fastest, not killing people in duels. I took up the duel-base mod and didn't run flags for a few months and I was once again very good. I went back to renegades and my skill went back down. I think it has been on a steady decline ever since then as I have not been back to base in a long long time... not to mention that I have not played tribes in allmost 9 months.