I also use the red FO front and all black comp rear. IMHO: It pulls the eye to the front sight where it needs to be.
I've shot numerous other combinations belonging to friends at my range; and for USPSA and steel shooting (iron sights), I prefer mine.
In all fairness, I wasn't 'practiced' with the different multi-color combos; but I honestly don't think it would hinder this old bifocal user.
Years ago, I played a different game--.22 cal Bullseye. For this game, where accuracy is the only goal, I still believe the best 'iron' sights are all black with a fine front blade.