Vern,
Spec pay and environmental allowances are very different beasts. Jumper is not a trade, it has no MOC/MOSID nor is the allowance pensionable, neither is aircrew, sea duty, foreign service, etc. When you are no longer employed in a position that is entitled to an environmental allowance, you shouldn't get it anymore. Getting Spec pay when posted out of your field is entirely different than losing jump pay when posted out of a para coy.
When I am posted out of 423 Sqn, I will take a pay cut, period. I will lose my sea pay and my aircrew allowance when I go to a non-flying position. And the fact of the matter is while you may not be flying, turning wrenches or fixing things, you can still be employed in a job that requires your expertise but not your skills, hence the reason you keep Spec/Pilot pay.
If you let everyone keep sea pay, aircrew allowance, etc just because they were posted, why not just jack up the pay rates and eliminate allowances altogether? But that would defeat the purpose of the allowances wouldn't it? Allowances exist to compensate you for your working conditions, flying is inherently dangerous, thus we get aircrew allowance when in a flying position. Sailing is also dangerous and uncomfortable, so we get sea pay to compensate us for that, something someone working in an orderly room doesn't have to put up with usually.
For the record, people don't lose their sea pay, or aircrew allowance for being on a TCat, I'm not sure the time required before you lose environmental allowances but I would guess if you're on TCat for less than 6 months you would keep it. I can't say for jumpers but I doubt that their jump pay ceases the moment they break an ankle.
My understanding of the foreign service pay, risk and hazard allowances that the injured guys in Afghanistan are allowed to keep is only the amount that they would have gotten had they stayed in theatre. It doesn't continue indefinitely.