I have had 5 different TQ's from 3 manufacturers. They all were quality pieces of gear, but in then end they were not for me. Many people love TQs. But there is absolutely nothing wrong with using a sleeping bag. Personally I think having it under you adds to the "R" value of the UQ.
My best advice is try them both, whichever one you dont like sell it on HF. Its worked for me.