Ok, i have done several Tests, you can watch them here:
http://www.mediafire.com/?djzqcwz1dd5
After i did those, i got pretty sure that it's faster getting the Triple Rod, for Train Engine Core, Hydra Mechaniloid, Anubis Necromancess and Rainbow Devil (Not sure since i haven't tested him yet. But for the others im pretty sure i save more than enough time.
Air Rolling Slash on those bosses cost time, jumping, getting high enough, 2 slashes per jump (4 frames wasted).
And Triple Rod is usefull for Submarine Skipping with a pogo jump on an enemy in Stop the Hacking mission. I think there's another point in the Capture Factory mission that i can use a Pogo Jump to skip something (I can't remember right now)
Also, this may sound incredibly stupid and non-sense, but Triple Rod Cancelling is slower than Triple Rod alone :S. And just by 1 frame.
EDIT: I will do some test with the Boomerang Shield, though i don't like the idea of getting it for this run, but i will do some tests with it.