I mean, you're probably going to get told to send it out for analysis...that color doesn't mean a thing...follow the owner's manual, etc, etc, etc. But I do think manual transmissions are probably "easier" on the fluid than an automatic transmission.
An automatic transmission fluid has to do more things...it has to perform hydraulic tasks, it runs hotter, it has to allow friction between the clutches, it has to lubricate, and it has to fight heat. The manual tranny has to lubricate and provide protection while supplying smooth shifts. It's generally a "thicker" fluid. It runs cooler. Having said that, I'd change the fluid. You'd spend the same getting an analysis done and changing the fluid isn't going to "hurt" anything, like it might do in an automatic transmission because of the friction qualities.