Has anyone ever used this site to sell iPhone? It says they pay you before you ship?

I found this site called upgradeswap and they say they will pay me before i ship the phone. They use paypal i guess to pay you.

I searched them on google and saw they have a 5 star rating on reseller ratings.

Do you think they're a site I can trust to sell my iPhone?

Source:
https://www.upgradeswap.com/#sell
http://www.resellerratings.com/store/Upgradeswap_com

I would just trade it in when you upgrade, that makes it easy and you won't get ripped off.

UpgradeSwap is legit, I used the site before.

Marcus - If he/she traded it in when he upgraded, especially at the carrier stores, he would get barely anything for it. The carrier stores thrive on the convenience factor.