Overflow of stamina? You mean you don't just hit accelerate for the first half the match? Overflow would require hitting 2 Aethers and being unable to use one Chocobo cure. Ofcourse you can just hold onto it long enough to use it.Sprint doesnt draining stamina for a good 3 seconds after Dash III. For exactly 3 seconds, as that is how long the sprint lasts.

I dunno, I'll reserve judgement untill I've tried a lot more builds so I won't say your wrong. But I find Dash being that broken a bit of a hasty assumption, in my opinion.