I don't have a clue why they would restrict the device like that. I wanted to do some static accuracy testing on these receivers, and I have an iTC on SF1, but someone here pointed out a technical document saying how NMEA isn't available unless you have a SF2 unlock and subscription. You can get NMEA out of a GS1/GS2 that is connected to an iTC on SF1, which is what I'll end up doing.

See the last post in this thread:
http://talk.newagtalk.com/forums/thread-view.asp?tid=72866