My rack is liftable now. It probably weighs about 65 pounds. If I get a molded and semi shallow case like I have now, I don't think it should be that much harder. Also, I'm thinking I may have to go with the 8u simply for rack cooling. I left my rig on for an hour while I was surfing, and it was uncomfortable to leave my hand on the GP3 because of the warmth. It's funny, it's generally power amps that are hot, but the Carvin doesn't really heat up that much.
I'm looking at possibly buying some 40mm fans and building a little 1u fan unit to put above the GP3 too. I guess I'll wait and see how leaving a space empty above it helps.