Don't worry about what happens at the end. In the end, the idea is you become a better writer.
I was invited into the very first, guinea pig group. I unfortunately got the boot because my final month there I was unable to complete the project (I had some unexpected life changes, was working 6 days a week, while moving to a different city on my 1 day off/week). It sucks, honestly. You unfortunately get NO lenience - do the 8 hubs or be removed, no matter the circumstances. The upside is, my best hub alone now gets 3x as many views per day as my entire account got before I joined, and I only got three months in.
My live-in-girlfriend is currently in the program (So I at least get the benefit of seeing the training) and it has certainly impacted her performance as well.
My point is...if you want to get better, join it. Don't join it for the $6/hub. You can make $6/hub through the bonus program if you're a good enough, and consistent enough writer. Join it for the self improvement. AND only join it if you know there is no chance that something will pop up in your life preventing you from writing 8 hubs per month. (Not just any 8 hubs, but 8 hubs under their guidelines)