Go Flex are the ones I have.... and I paid quite a bit less than noted above, a lot less. They were a lot more than all others but on sussing the level of trust in the manufacture was far higher and for my application trust is very important.
The key is while flexible they are still quite solid. The cells are mounted/imprinted/something like that onto a panel that is sort of like the stuff they use for real estate signs, a flasher version of course. It is flexible but nothing like a sail cloth for example, it;s more like say cardboard. So while it can bend it won't fly like a flag nor can you 'roll' them up so to speak.
So I'd say the Go Flex are semi-flexible rather than full flexible, they are certainly not stiff.
As mentioned above I can walk on them. I have bungy on each corner and just hook them where it gives them the best sun blasting. I did consider poles and mounting them on top etc but the lack of flexibility and windage I couldn't live with.
The other day I had one lying on the kitchen bench not in direct sun away from any windows and the meter was reading 18.8V. Not sure if that means anything but I thought I should like that.
Mine are 100Wers.