1. If it was a bug it would be in the bugtracer or it would be commonly discussed but no warrior i know complains.
2. stats are based on old solid sources you can lookup info on twinhead on most, but an elite's difficulty depends on its race, lvl and abilities for example an elite Giant would be harder than an Elite Dwarf in most cases unless u kite ofc.
3. threat generation is 100% correct, i tested this while having the threat displayed from the server. This was while i was part of the test crew btw and i cross refferenced with it old addons from the time and other sites and it matched perfectly, i did this in order to double check just to be sure and the only bug i found after going through them all was a earth shock & rockbiter which shamans wouldn't ever use in raids anyways but it was fixed right away. warriors where ofc the first to checked and they where spot on 100% correct.
note: if you're in doubt you can apply as a tester and request to test threat again and then try to dig up old sources but i really doubt ur gonna find anything "wonky" ^^
I wonder where you heard it but my guess is most likely someone envious, anyways if in doubt just go to twinhead 99% of the cases are public and you can see the whole procedure of most along with sources used.