Never buy a MXR Double Shot. That has to be one of the worst gear purchases I have ever made (and it was the last time I listened to a guitar magazine review

).
If you want a great pedal, buy a DS-1 and have it modded. John (aka Stratdeluxer) does (from what I've gathered) amazing work and for a very good price. You could end up with an extremely good pedal without needing a lot of dough. You figure the MXR Double Shot used to be $120... a DS-1 is $40 + $35 or so for it modded (not sure on the figures, you'd have to ask John about that) and you'll have a much more superior pedal while still saving cash.