I've got the giles on my bike... they're cool.. but I got them for the looks... don't really seam that much easier to adjust the chain than before...
BUT... i have heard from several people that they've seen cracks develop in these... both in the Giles and other brands... so be aware of that...
I'm happy with mine... though I'd probably save the money if I had it all to do again as I'm selling the RR