Yonez:
I last served in MW some 3.5 years ago, and I have very recently been in the presence of E3 hired_help/gurkhas. I hope I dont have to know too many non AAC capbadged QHI, but I am sure one or two will scrape on through. If you havent been transfered by the time you get onto a QHI course then you might not be the best piece of chalk in the box, and if you have got onto a QHI course before transfer, then perhaps you have gotten onto the course before you should have. I stand by my original comments, the AAC boarding system, although not faultless, is about as fair a system as you might hope to have.
Always BIW:
The AAC is manned by proffesional aircrew, the same as the airfarce and the FAA. It is rare for a pilot to do one tour and go back to their original unit, but not unheard of. How many rotary airfarce pilots, take 3 - 5+ years to graduate to front line, then do only one tour and bang out? I suspect all three services have the same loss rate/value for money.