As for the assumption, you seem very deadset on implanting gurps, but so far the only other person who said gurps might be a good idea was someone who I have never seen before in the thread.
And you think I won't want to be playing this game if we don't? I'm more likely to quit because of that assumption than because we don't use GURPS.
As far as balancing goes, GURPS is balanced towards GURPS, if we try to make some sort of hybrid, we are no longer as guaranteed to be balanced as you think.
I don't expect perfect balance. However, consider two things:
1. Most abilities we're concerned with are ones that are fairly rules-agnostic. Flight, for instance, is pretty simple; you fly or you don't. Modifiers affect how you fly in also rules-agnostic manners, like "you will be unable to fly if your wings are hurt" or "you can fly in space now". The non-rules-agnostic ones are also not much of a problem, if we're not worried about perfect balance (as opposed to just guidelines that make it harder to accidentally make an OP or UP character and easier to judge if a character is of an appropriate power level); for instance, since the human average for statistics by your system is 5 and by GURPs it's 10, any stat modifiers would be halved. There will be some gray areas, but it should be pretty easy to apply.
2. Imperfect guidelines are better than no guidelines. You haven't said a single word on how to determine if some power/perk/set of powers and perks is balanced or OP, save that obviously OP ones are vetoed...with no suggestions as to how to make it non-OP. A GURPS hybrid would give us such guidelines, and unless you can provide examples of something that's balanced in GURPS but not when translated to RMG-3.0, we'll have no reason to think that the discrepancies will be significant.
Cado's ideas are pretty neat.
Cado, I'd imagine your second point becomes all the more complicated, when people start just claiming they had no controle over their abilities to dodge punishment. suddenly you have to doubt everyone who claims the fireball who blew up their neighbours yard was an accident and bam, eventually that excuse will no longer do.
I think it would work something like an insanity defense; if you can prove that you lacked control over your powers, rather than being jailed you'd be isolated so your uncontrolled power wouldn't hurt people and you'd be subjected to treatments to either get your powers under control or remove them.
P.S. Your argument roughly mirrors an argument that the insanity defense would lead to everyone claiming that.
Now with everyones abilities being put in rules and becoming generaly less versatile, Kyle becomes more versatile in comparison, to the point where it is utter GM mercy that Kyle is even allowed, as simply, his stuff stretches rules quite a bit. Add that armor on top, and Kyle is more designed to be a powerful bossfight than an actual PC
Don't be absurd. Bosses are usually much more limited in their array of abilities.