My mate has a tensioner like that on his GasGas EC300 enduro bike. Although instead of a thumb wheel, it uses a larger bolt (bigger wheel) with a normal nut on it, so you can use a spanner on it. If you get that thread dirty, which could happen, then you could get the thumbwheel on it stuck, and by the looks of it there isn't really a way to get any tools on it to help it turn!? I do like the intergrated tensioner idea though, but I think a normal nut on there with enough space for a spanner would be better. Then if the nut does get ruined, you can easily replace it!