I am not sure this answers your question...
In additon to what Ironhawk stated... which obviously would effect reps, etc.
In my experimenting I found that if I mistimed my combo moves thereby 'skipping' them, that it appeared I would receive more reps. The downside was length of time/number of attacks it took to defeat the enemy. Taking an extra minute... wearing my fingers out mistiming strikes... wasnt worth the 5-20 more reps I might get. In the long run I determined although it was neat to change up every once in awhile, that it wasnt worth the extra time for the few extra reps.
Zeppers Lvl40
http://pirates.teamofx.us