I can't believe I missed all this while I was on vacation,
If you do it then I would become a paid member as long as you have lots of cool prizes on the wheel I think it would be fun. I love the game and see it as a way to support it. I think the argument that if you didn't become a paid member you couldn't upgrade is wrong. It puts the people willing to put money in at a slight advantage but no more so than paid fame resets or moves does now. And it wouldn't necessarily cost $120 a year because you could do it one month when you felt you needed the boost and then not the next.
I liked the put a cap on the jackpot idea that was suggested though I know admin has already tossed the idea. Here's why. After the cap had been reached the extra could be used to do other things for the paid members like treasure hunts for just them or it could go in toward lowering cashout which would help everyone.
You might try different levels of paid memberships with maybe a cheaper one that doesn't get to spin the wheel but gets a certain amount of gold added to their account a day.
I think the possibilities are endless and as long as you keep the free memberships intact then I think it would only help the game grow.
P.S. Don't wait until you get it perfect because I suspect you'll constantly be changing and adding to the game to make it more challenging and I'd like to see this at some point implemented.