I’m not going to spell it all out for you, but spend some time reading over Bryan Eisenberg’s insightful post surveying the changing face of Amazon.com’s Add-To-Cart button and I think you’ll get some idea.
Here is one key line from the post…
Just because Amazon does it, doesn’t mean you should. They make decisions based on their business needs, not yours.
Sweat the small stuff. It can be amazingly important.