Sorry about the thread necro, but I've been designing a team of frames that focus on speed and I had an idea for a double-green ability that I hoped I could get some feedback on. I figured this was the best thread for it rather than starting a new one.
The ability as I've currently written it is that if a frame uses a 5 or more for its movement, it may use one remaining

or

for defense. The idea is to effectively simulate the frame moving so fast as to be especially hard to hit. The frame doesn't need to actually
move 5+ units of distance, just use the 5+ as its movement die.
I figure most of the time this wouldn't give the frame any special advantages beyond a bit more flexibility. Say a frame gets 5+ results on two

, but either doesn't have a

or gets a crap roll on it. It may use one of its

instead of using up a

. On the other hand, if only one

results in a 5+, then using

for defense could be preferable anyway.
Very occasionally, though, this could make the frame very strong defensively for a single turn if it has two green d6 and a green d8. If a frame rolls a 5+ on at least one

, and a 7 or 8 on a

, it may use the

to move and use the

for defense, giving it a much higher defense for that round than would be possible with blue dice.
I haven't had the chance to playtest this yet; it's just something I'm toying with in planning out a team, so I'm eager to hear any thoughts everyone might have. Is this overpowered? Does it make taking other systems less attractive? Or do you alternately not see this as being an attractive enough system to justify spending two systems on movement?