Balsy, I have an X52, and used the SST software to program my secondary fire button as a single key press of .01 seconds, just to check the yak's ROF. Normally I don't use that, since it won't repeat - ie, I can only fire a single round per pull. Typically it fires a few rounds when mapped "normally".
I don't know how the CH software works- the only CH stick I've used was an old gameport F16 stick (circa 1996), and the software for that was really limited compared to modern CH or Saitek gear.
I'm guessing this issue (very short bursts fire normally, slightly longer bursts exceed the ROF) is a timing issue for the repeating keys, but I'm not exactly sure. I may try to do another test if I can figure out the approximate timing to start with.