Years ago I had a cheaper version of one of these folding creepers, if I remember, it had a 350lbs capacity (I weighed around 200lbs then). Its still around here to remind me to never again buy one.

When its laid out flat, the weight is distributed between the 6 wheels and other then pretty easily pinching one's self when it flexes as it moves across the floor, (it also pinches easily when its changed between the seat and the creeper), the 6 wheels in the creeper position hold up pretty well. The problem is when it is in the seat position, all the weight is distributed between 4 casters. Those 4 casters don't hold up very well.

The seat height is pretty high, if you are working on a vehicle on a floor jack, you will be ducking down to get under the fender and will keep leaning over while you work. In the seat position, the framework had a lot of movement. It positions past over center, so it won't fold down (there is a locking lever), but you really can't sit on it and roll around because the 4 casters can't support the weight. The looseness in the frame gives you the feeling of it being unstable in the seat position, if you try to roll around, but for however long the 4 casters lived, it never did falter in the seating position, but it sure felt like it could have at any time.

Maybe the design has changed, but I doubt it. Gene