Hi there, I'm probably going to have to find another facebook plugin but I thought you might want to know about the conflicts I have found once this is enabled.
Formidable Forms plugin:
Recaptcha always produces an invalid code error when simple facebook connect is enabled.
WP Customer Reviews:
Displays the revie button twice, no reviews yet but it may display the content twice, I don't know. Support for that plugin suggest the problem lies with simple facebook connect. http://wordpress.org/support/topic/plugin-wp-customer-reviews-review-button-shows-twice-with-simple-facebook-connect?replies=2
Albums did not displaye correctly with simple facebook connect enabled. Added a fix I found on the topic below to alter nextgen to work with simple facebook connect.
There seems to be a common theme though that for this plugin to affect 3 other plugins that there is possibly an issue with sfc.