Plastic and humidity is a combination that is guaranteed to send you right off the deep end.

If you plan on doing a lot of 120, I can't recommend Hewes reels highly enough. Once you get the knack for pulling the film to the right just enough so that it drops over the rail above the clip (then push down on the clip and feed the film back to the left, over the clip), loading 120 reels becomes pretty easy. The SS reels don't care how humid it is, and if you don't go out of your way to bend them, they'll last you forever.