I finally bought a lift last weekend. I chose the Atlas KOH9 overhead 2-post model based on the recommendations from the GTGuys to get a 2-post with asymmetric arms, and based on ready local availability and price. Yeah, it's made in China, but I called and emailed Rotary Lift, and they have a goofy 20th century way of selling through distributors, and the distributors want to have someone give you a sales call and discuss the options. After a couple days of waiting, I said the hell with it, and went to Greg Smith Equipment for the Atlas. It was only $1595 (I don't understand how they make a profit at that price), and I could pick it up from their warehouse in Delaware on Saturday morning, without having to hassle with shipping to some intermediate shipping handler and having it pick it up there, so that sealed the deal. With a 9000 lb rating, it's overkill for my meager needs. It also has a 4" low pad height, which fits under the (non-lowered) GT without the need for 2 X 12 ramps. The Rotary Lift AT07 has even lower pads, at 3-5/8", which might have swayed me to them, but like I said, they didn't call back.
I set it up loosely this week and I have to test the location of my cars relative to the columns to make sure I get it optimally positioned before I drill the bolt holes in the concrete. More later and pics after I get it working. As Empty Pockets suggested above, I plan to bolt some braces from the tops of the columns to the roof rafters to give it more stability and resistance to tipping. We actually had a decent earthquake in Virginia a couple years ago...