The Body Solid GCEC340 machine is sturdy, and it feels sturdy when using it. I had to phone a Body-Solid sales representative in order to find out what the weight capacity is for it. He told me that it can hold 400 lb of weight plates plus 200 lb of the user's body weight, for a total of 600 lb. Why in the world is this information not included with the machine?
Some of the assembly was difficult. Before explaining, I should note that the Body-Solid web site contains a PDF file of the owner's manual, although it is missing the assembly diagram. But it does show the hardware and parts illustration sheets, which you might find helpful in understanding my explanation of the difficulty. Part G contains a piece of metal (let's call it a dowel, for lack of a better word). The dimensions of the dowel are 3/16" x 1/4" x 2". I had to pry the dowel out of part G in order to be able to insert part G into parts D9, D, B, and F. Prying it out was difficult, and it took me some time to figure out how to do it. It also took time to figure out that prying it out was necessary or even possible.
Here's what contributed to the difficulty: The assembly diagram shows the dowel already separated from G, and the dowel is represented by a line only 3/16" long by 1/16" wide, barely larger than the dashes that link each part in the diagram. And the dowel is not labeled in the diagram, nor is it shown in the hardware and parts illustration sheets. It should have been labeled as a separate part or piece of hardware, and it should not have been inserted into G at the factory, in my opinion!
After inserting part G into parts D9, D, B, and F, I had to hammer the dowel back into part G, with the assistance of a nail set, in order to get the dowel all the way into the slot. Nowhere in the instructions was this procedure explained.
Regarding usage: In order to get one's left leg under the corresponding upper leg pad, the upper leg pads (as a single unit) need to be removed. After sitting down, then the upper leg pads can be inserted back into the machine. This is an inconvenience because it slows down a workout when doing leg curls, assuming you wish to stand up between sets to stretch and/or to alter the number of weight plates on the machine. (The upper leg pads are not needed for leg extensions and can be removed for this exercise.)
The "pop pin plunger" for the upper leg pads needs to be unscrewed by about one and one-half turns in order to raise, lower, or remove the upper leg pads. I'd much prefer it if the pin could be fully pulled out and reinserted while the pop pin plunger is fully screwed in.
For leg curls, it is necessary for me to remove (or nearly remove) the upper leg pads so that I can get my legs onto and off of the lower leg pad. I like the thickness and firmness of the lower leg pad; most likely it won't ever hurt my shins when doing leg extensions. Also, the handle bars are well positioned for me. (I am 5' 10" tall.)