Has their ever been any plans to move Gambit out of the X-Men Universe and more into the general Marvel U, where teams like Thunderbolts, Mi 13, Secret Avengers etc reside, he just seems a bit wasted on the X-men teams.

No, can’t say that there’s ever been any consideration for that. Partly because the X-Men are a part of the greater Marvel Universe, so you’re pointing at a distinction that doesn’t really exist. But I know what you mean.