Is 'Early Adopter' Pricing Effective?

As a small startup, we're about a month (or less, I hope!) away from launching our product. I've worked out a business model and run it by about 5 potential users. Each of them was confident that the 'price is right' however I'm not 100% sure.

I've seen a few companies (e.g. Recurly) do 'Early Adopter Pricing' where they offer a certain price to people who sign up early. That price will be grandfathered forever.

Has anyone here experimented with this? Is it better to just set a price then change and grandfather people? Or does the 'early adopter' discount drive sales?