A_Bear covers the price change for your package on the next page of your link, but doesn't get into any channel differences. My guess would be you'll keep all the same channels, except cloo which most everyone is losing.
I think the only people that need to worry are the ones thinking of changing to a Choice Extra package.
OK, I must have missed that, since I read that thread a while back and just remembered that table. I just called to add unsupported MRV, to be sure I could with my current package. While on the call, a CSR that seemed pretty sharp, said I would be grandfathered with that package.
I had the beta version of MRV and liked it. When the beta testing was over, I tried to add MRV and they said I had to go with a current package. The package price for the same channels was higher, so I just said forget it. With the same package, today they were able to add it for just the $3/mo. If I had to change packages to get it, I was going to do it today, so I would keep the few extra channels, like NHLN. Already tested MRV, it works fine and I'm happy. And they threw in 3 mo's of the Sports Package for free. Can once again watch pre and post-game shows of my NHL team.