Well, I chatted with my LBS and it seems I'm not going to be upgrading my rims anytime soon. Turns out that if I go tubeless, the rims will be lighter but the weight of the tubeless beasts will put me back to almost where I was with my original equipment--Specialized/Alex RHD rims and Fast Track DC tires.

OK, so maybe I just need to accept I'll be a choo choo train on hills.