Why not just get the standalone and transfer everything you have. Doesn't look like you have the Mirage, which is the only thing that won't transfer over.
If you're one of the people worried about payment issues, I use paypal, and have never had a scam/fraud problem. If you're worried about the long updates, they aren't that often, and as long as you keep up with them, it's really not too bad. I used to use the Steam version, but it feels so limited in what you can/cannot purchase.