i used to use all novak speedies for about 9 years until recently, never really had a problem with any of them exept for GT7 model which blew a diode internally... and i got replaced through novak with a new or referb model looked b/n when it came.
i am currently running mrt mx pro speedy in stock an modified and so far have found it to work exeptionally well.
i tell a lie above, i also did use a Mtronics "prodigy" one that came with silver outer case, it was also a brilliant esc until someone plugged batteries in reverse and she went pop and let the smoke out... got it repaired but it lost alot of punch an was never the same with the new smoke so i went back to novak.