I can only speak from my experience and they Alpro's did help my knees.I've just invested in a new pair of Alpro pads, my first pair, I've been using the Rubi pads for years and go through about three pairs a year as the strap area always splits, anything else I tried always caused discomfort so going to the Alpro was a big change.
The are easier to put on and adjust from time to time with the Velcro where as the Rubi ones had a clip to fastened. I don't think they will reduce knee pain as the tag line says but I think they will reduce the fatigue of a long day on your chips and peas.
I would warn you though that the first couple of days using them my knees were in pain, I thought I had wasted my money. Then miraculously they became the most comfortable one's I ever worn. They take a little while to mould to the shape of your knees so if you have any discomfort initially, just stick with them.