Actually when you get comfortable with doubles it tends to put less strain on your body, whereas playing singles has you naturally go and swivel your feet which looks really bad for your knees imo.

Its not that hard to learn. Its actually really simple (it was for me)

It's a bit more technical to get a hold of but doubles are the way to go. You're literally expending half the energy and also keeps your body in a stable position so you can get around the set nicely. It's not the end-all though, you've gotta master 8th triplets/dotted 1/4 notes as well and doubles wouldn't sound as clean. Basically you should practice all techniques and figure out how to make it work for your body type and style.