I would ask them how much access to the system the public have, that's really the only reason it's cheaper. Floor models get discounted because the general public have the ability to play with them as they see fit and, often times, most people don't know what they're doing.
Generally the store will do a clean install of the OS before you get it anyway so I wouldn't worry about anyone having damaged it software wise but just ask. The price is good though.
You can get one from apple refurb for $1,419 and you shouldn't even be able to tell it was ever used, plus you can use their free printer rebate, and it comes with the same warranty as a new mac. I'd definitely do that instead.