Nevermind, I played the demo again. Then went "what the heck" and bought it. It's at least worth the ~$20 I spent on it. And if I really like it, it'll be worth the $10 I spent on it.
The way I see it, if the appeal of this game lasts only a short while then it was only $20, if I end up getting rebellion it will be like I spent $10 to play it till rebellion comes out.
I'm still curious about how long I have for the Upgrade discount.