I started doing Simplefit a few years back and I still lurk here every couple of weeks. I had to come out of the shadows to answer this. I have this pull up bar and it works really well.
Because of the fact that it goes together with no tools in 30 seconds (really!) it does have some slight play to it. It won't work for kipping or any kind of swinging movement. For regular straight chins, pull ups, hanging ab work, etc. it works great. I also do ring push ups on it. As long as your pushing down and not out your fine. (I hope that makes sense.)
I've had no problems using it and I started at 259 lbs.
Also, customer service is excellent. The gentleman who runs the site had my unit to me in good time, less than a week. When I received it, Fed Ex had mangled the box and lost the actual pull up bar part. We contacted him and I got a replacement free in 3 days!! A+ service.
I know this sounds like an ad but I assure you I'm just a very satisfied customer.