Since when is being "double jointed" an advantage in other martial arts?
Well, coming from originally a gymnastics background when I first started training (Kenpo Karate)a lot of the warm ups involved getting used to doing the splits etc. (presumably for high kicks..???)which obviously in my position werent really a problem.
My joints are very flexible as well and I have become a lot more careful to keep them from becoming hyperextended. With shoulders and wrists that dislocate very easily, I've had to work on ukemi that do not stress them too much. Sure, people will have to try "really hard" to pin me to the point that I hardly ever have to worry about pain compliance pins, but these days I usually tap out when I'm immobilized...
In any case, all I can say is to be careful with your overly flexible joints. It's nice to have flexibility throughout the body, of course, but I've found from personal experience that having flexible joints means that they're usually the first things to get injured in aikido practice...
This is my point exactly, even though it dosent hurt me its only when I started Aikido training (and I was becomming aware of pressure on certain areas that I never noticed before)that I realised that hey, maybe I'm doing some unseen damage here which will come back and bite me in the ass in a few years, this situation never arose in other training (gymnastics/Karate).
So thanks to the info I've gotten from my teachers and from this website I'm doing exactly as you've suggested ie tapping out when I'm immobilised and generally just being more aware.