I have no experience with Connections. I can tell you that some of these programs are less flexible about how they can be used than others. More flexibility tends to be preferred than less, but really, that's specific to your family and your needs.
From what I've heard from homeschooling friends who have used these sorts of packages, I'd avoid a program that requires you to log-in at a set time each day. That can be hard to make work around field trips and other lessons.
I'd also look for flexibility in terms of material. Can a GT child work on, say 5th grade math and 8th grade English? Or do you have to use/pay for each entire grade level before you can move on to the next? That can be a serious hassle.
None of these comments are specific to Connections, but they're things to watch for in general.
I hope it might help, even though it's not what you asked for...
