So the aluminum rack is a lot lighter, huh...cool.
When I had my Swamper on the roof (hasn't been up there since before the lift) I could tell it was up there, but it wasn't a huge deal...did worry me a few times offroad though. I guess the rack + Hi-Lift shouldn't add more than about 60 pounds over the weight of the spare (does this number seem right to you guys) ?
Does the aluminum rack (or at least the parts you've seen) seem as sturdy as the steel one?