Managed to get out for a sneaky mid-week ride around the trails and byeways in the Surrey hills, so here's a couple of pics of my bog standard version 1 Pod K4s (which I picked up for well under £300). As you can see they are a "floating knee cap" design, so different from the new ones, but nonetheless fit perfectly under standard Off Road trousers, here I've got Klim XC Lites on.
I've got the hinge set up so I can't quite straighten my leg which I find works best for me when I'm standing on the pegs. I decided to go for Knee Braces as usually my graceful dismounts are from a standing position, and I often (but not always) seem to contact the ground first with one of my feet/heels before hitting the dirt. I managed to tweak my knee a couple of times so reckoned I was more likely to get a hyper-extension or twisting injury off road so bought the braces. They are comfortable for all day wearing and seem to take a bit of the weight of your knees when standing up for prolonged periods. Overall I've been very happy with them.
I don't use them at all for road riding, but that's just my personal choice as I prefer to stick with the D3O armour which came with my road kit.