I've never used any Keeley stuff, but it did get rave reviews in Guitarist last month, and everyone always goes on about how amazing they are...
I can't see the appeal to be honest though - why take something relatively bad (DS-1 for example) and try to improve it, when you can buy something that was built good to start with. Surely there's only so far you can improve on something
Maybe I've got the wrong end of the stick, but:
Keeley Blues Driver = £81
Shipping to UK = £16
Total = £97
Now, I can get a Jekyll and Hyde overdrive for £120 - and to me that seems the much better option