I go to a shop here in Toronto, Canada, called Long & McQuade. They're great for customer service. One time, I wanted to see if I wanted a delay pedal, so I bought it on my credit card from them, tried it out for a few days, changed my mind, and they gave me a full refund. I've done this before with other things that I ended up buying afterwards, but each time they said "Pay for it now, take it home, try it out for a few days. If you don't like it, the worst thing that can happen is we'll charge you rental for three days. If you want to keep it, then keep it."

I love them for this, and it's the only place I go for gear.

Maybe your guitar shop won't be as flexible, but you might want to consider renting the gear for a few days (just a few bucks).