I have the tire changer you linked and it works great for me. Have been using it for over four years now, has paid for itself 100 times over, haven't had any issues with it. I did make a base for it though, just used an old 2x12 I had and made an "X" base. It was a little tricky at first, but now that I got the hang of it, I can swap tires quick. Even the bead breaker works decent. Rear tires are a piece of cake, no issues with those. I do have some front wheels that that give it fits, something about the inside bead it doesn't like. Those I just break out a board and use my truck!
I have found the key to swapping tires with this machine is letting them sit out in the sun for a while. If you have to swap a few sets, it is a little bit of a work out, but still better then paying some one to do it. That is exactly why I bought changer, local bike/atv shops charge $10 a pop for a tire (Discount tire wanted $20 a tire!) and some of the shops won't even touch the tires unless you buy the tire from them. I can't even think of how much money this thing has saved me over the years.
Of course, I own multiple sets of tires for racing, so I end up changing alot of tires. If I only owned one or two quads and just trail ride, I would probably just take them to a shop, because I probably wouldn't have to change tires often.
Doug