Bel Ray gear saver is fine. I'm not sure how they come up with their 80W claim but it's much thinner than a 80W gear oil for an auto rear end which by the way would kill your clutch!
Honda makes an oil for their CR line that is similar to the Bel Ray too. I simply said 10/40 because that's what the manual called for back in the day.
Two stroke trannys don't get gummed up but a quick fill, run, drain won't hurt anything.
The new stuff is most likely an improvement, good luck...