If your website is better suited with real usernames (eg - not a entertainment virtual world or game etc) then suggest go solely with Facebook Connect. It will

If your website is better suited with real usernames (eg - not a entertainment virtual world or game etc) then suggest go solely with Facebook Connect. It will simplify development for you and make it clean for your new and existing users. If Facebook changes the policy, you can always adapt at that time (as will lots and lots of other people). Better spend coding cycles on user features not planning for unknown future permutations?