I like Gaele, he's a solid little boxer. Decent speed, and decent pop, good work rate, and all the intangibles.
However, I think he's peaked at the MW division. I don't see him being able to beat Martinez, or Golovkin. Since Golovkin is obviously the lower reward fight, I would avoid that fight at all costs (which I expect him to do, unless HBO offers him a seven figure payday, which I doubt).
I'd try and get the Martinez fight next. For his first fight back. With him coming off some crucial knee surgery, he might, MIGHT be able to beat him. I mean, Sergio's style is all about his legs. If his knees are shot, he's like a prized racehorse - gotta put him down. . . But even in the most likely scenario of Martinez beating him, he'd have nothing to lose, and get paid a lot better, and get more recognition than fighting Golovkin.
Since Martinez can't return until May (that's the tentative date being thrown around now by Lewkowitz), I'd just take a tuneup/stay busy type fight against a top 15-10 type guy in December-January. Perhaps a Darren Barker, Macklin, Andy Lee, Craig McEwan, etc. ALl of these he should win, but get some good work in.