I am not sure if i am right but cant be possible make identification by IP? Also there are already logs ofc and i think its pretty easy make stats for it. (not for me tho).
Maybe on start could be stats just optional. Time show if its good or no. Also it could be for start only for duel servers, which is less hard make stats for it than for CTF.
I am big fan of stats. But how said fluff not EXP system as on ZD , i think it kill game. I think best could be only frags/deaths/frag ratio/. How said fluff winning streak could be good, not loosing streak which only make game bad and players can stop play. (yes make only positive stats, nobody want look on stats when lost 5x in row and etc.). And also time spend in game could be cool.
There could be some duel ranking system, when for beat player which is high evaluated it give players more points than for beat player which is lower evaluated and etc. There is really a lot stats which you can make. But for start there could be just stats more above, which could be cool :).