My wife and I have been using the 12.9T for a month now and have been extremely satisfied with our purchase. We were able to try out the treadmill and comparable Sole models at Dick's Sporting Goods before purchasing and were far more impressed by the sturdiness and feel of the less expensive Livestrong models. Assembly was straight forward, and completed in less than an hour...just make sure you have two strong people to move the box to where you need it. Don't unpack it until you have it in the room where you're going to put it together.
So far, we've put it through its paces without any issues. We really like the fitness journal. It's very rewarding to see total stats (like calories and miles) stack up and compete against each other to see who's logging more workout time...we enjoy a little friendly competition. We were also very impressed with the speaker system on the Livestrong equipment. We use the speakers to play music in the workout room while doing other exercises as well. The sound quality is very impressive.
This is the best treadmill we could find in this price range and would certainly recommend it to anyone looking for gym quality equipment for their home.