Considering going 'tubeless' for my back wheel.

I currently run a Mavic 721 rim with a Maxxis high roller singleply tire. Even at 40psi I get punctures quite often and thats just on xc rides. For dh i use dual ply tires but there far to heavy for xc

So, how effect would a tubeless conversion be on my current rim?

Or

Would you recommend buying an 819 (tubeless specific) and using that instead?

How difficult is it to build up a wheel with a tubeless rim? Are they trickier?