I agree on the RC Boost, it's an excellent tool to have. Lots of versatility in that little box and very well made. Don't know much about the Keeley because I've never had one but I've read a lot of cool things about it. For the money, you can't go wrong with the RGW Bad Bob or Catalinbread Super Chili Picoso either. What's cool about these is that they only have a single vol. knob so there's no tone controls to dial in and they're both very transparent and quiet. If you want to spend a couple more bucks check out a Paul Cochrane Tim pedal. It can be used as an overdrive or as a clean boost if you'd like. It's sort of an RC boost on steroids! It almost becomes a part of your amp, sort of an extension of the amp. Another pedal with a lot of options to work with. These are the ones I use through my old Marshalls to give me a little added boost for leads. They're all different flavors.