My brother and I carried one with us when we rode from Canada to Argentina a couple years ago. We had just the basic model (the connect wasn't out at the time), and sent an 'ok' signal from it every night. You can add a bunch of email addresses to your mailing list that it sends your messages to - there are different lists for the 'ok' and the 'help' message, so you can put different people on each if you want. It didn't seem like there was a limit to the amount of email addresses on it. You pay a year subscription - it was $99 Canadian dollars for the year at the time, and that gives you an unlimited amount of messages, so you could send it 10 times a day, or never in a year, and it would cost the same. You can set it to track your route, and then it automatically sends up a signal every minute or so I think, the only thing is that really kills the battery. For us, we used it every day for over a year, and I don't think we ever had to change the battery (just AAs I think). But I think they said it would last about a week if you had the 'tracking' feature on.
I haven't actually used a connect, but from what I've read before it looks like you can still have the normal functions of the standard one, but then you can send custom text messages using your phone if you want, without having to have cell coverage. If all you're looking to do with it is let people know you're ok, then I think the standard one would be just fine. But if you're looking to send out individual little messages (just found a sweet 14% grade!, or something like that), then you'd want the connect for sure.
Hope that helps!