Just need one on bottom limb usually, theoretically the limb tip is worst place to add weight performance wise, but you probably won't be able to tell, just get the rubber ones recurve model, doesn't hurt to have one on each end if you're a clutz like me, nothing to worry about with them unless you pack it full of sand or something then you might want to clean them out, I used to use them all the time but haven't in several years
I use leather ones, easy to put on and don't weigh much. I've never had any issues or noticed any change in arrow flight. This is a pic of one on my longbow.
I use the black rubber "V-ish" shaped ones on recurves. Easier to put on than the rubber tube style, although if that's all I have handy I'll trim about 1/4" off to just cover from the tip to the string grooves. I'd only worry about moisture if I knew the tip was scuffed before adding a protector, in which case I'd have touched up the finish anyway. Absolutely no performance difference I can detect. Never tried the leather ones, but the rubber styles aren't coming off. Plus I'd guess the leather would hold moisture, which isn't good in case there is a finish scuff under it...
Leather ones, particularly if made from goat hide, are tough and durable...and the dry out wet. I would be a little cautious of the rubber ones, a little heavier and can retain moisture in the cup. YMMV