I've used Moly-60 on my bike. I do like it, but I have also noticed, like Paul Glaves of airhead-fame, that it does tend to dry out as it is, well, paste and thus less liquid than grease. I think for my next spline lube (and what I did on my final drive splines last time I had the wheel off) I would mix together 30%-50% of Moly 60 paste with a very sticky , tacky grease that would tend to keep things stuck better and not dry out so fast. A good sticky grease (but which doesn't seem to have Moly-disulfide in it by itself) would be Wurth SIG3000 - which is not easy to find (I found a Moto-Guzzi online supply shop that carries it but no where else lately).
A company in the midwest of the US called Guad Dog lubricants makes a product called GD-525 with 30% moly and a sticky grease premixed together and is apparently highly recommended for greasing motorcycle splines, but they charge $25/ 4 ounce jar, which seems excessive to me, but many are happy to pay for it - 4 oz of the stuff should last for quite a few spline/final drive lubes for the average biker.
Using straight Moly-60 is probably better than a number of choices, but I guess that I'd suggest that if you use it straight, plan on going back in to redo the job in a couple years as it will have dried out by then and need replenishment.
