I have G-Form knee and elbow pads. As an old, fat, slow guy whose tires rarely leave the ground, it's kind of silly for me to be wearing pads, but that little extra protection makes me feel a lot more confident.
I still remember a low-speed fall I took at Blue Mound many years ago -- that sharp rock to the knee hurt for months. It's this memory that drove me to purchase the pads.
I couldn't be more happy with the comfort of the G-Forms. They are stretchy and low profile -- they don't feel that much different than wearing compression tights.
In terms of crash protection -- I thankfully can't tell you how well they perform. They look like they would be a lot lighter duty that the bigger, hard-plastic options, but I really don't know.
I do have one durability concern. With both of my knee pads, the top part of the pad tore away from the fabric sleeve (while pulling them onto my legs). Either this is a weak spot in the design or I need to be more careful about where I grab them when putting them on. Both elbow pads are the same age and they don't show any signs of wear.