A couple of years ago one of the FS Controllers decided that he couldn't cope with it any more due to stress and that he wanted to be a FOM. After an extended period of imprinting his arse on the crewroom chairs with the occasional visit to the therapist, a short detachment to High Wycombe was found for him. It seems that he was upset by the attitude of some of the FOM's down there that they didn't welcome him with open arms. On his return and after another lengthily hold which gave him the opportunity to avoid anything that might be considered constructive, the powers at be offered him the opportunity to remuster. First he would be detached to the other end of the country to shadow a PFOM for six months then an out of area for four. Only then would he be considered suitable to be placed in a FOM's post. The proposal was not to his liking so he PVR'd.
This individual was well known as a complete chiseller and it was very obvious that he was afraid of working for a living. He gambled on being pushed into a quiet corner and left to fester, I'm glad they saw through him. He wasn't the only one, a Sgt deliberately dropping a number of check rides hoping to have an easy time with just a couple of tickets and a Flt Lt supposedly going wibble to miraculously be re-branched to PTI within weeks.
In previous years I believe it was possible to be selected on both boards, for Controller and FOM. I think that it is most unlikely now, I know of a few who were acting Corporals going into JATCC so if they failed to check out, potentially they could be back to SAC. The OCU proposal is interesting, essentially it's formalising the system that CATCS has been doing for years. Pushing out people with marginal passes to see if they make it in the outside world, if they don't let the units make the difficult decisions.