Personally anything that says Combo: Skill2342 - is fine with me. Let the previous button turn into the next part of the combo. Where there are choices in combo, let it end at the 2nd stage. For example. Instead of 123, 124, 125 - The 1 should turn into 2, then I have 3,4,5 as separate skills.

Or just put it an option in config - Personally in PVP I think this was handled well. The 'I'm so leet' people can say it makes the game too easy, but it was never hard to press the same monotonous combination to begin with.

That way the difficulty can lie in extra skills and not gauge generators. (And the precious 15oGCD's that people appearntly miss weaving)