I'm currently on the SERO 500 plan, but will soon be switching for the Hero. It was a good 2 year run on SERO, but have to give it up I guess.
The bright side is, if you call in to retentions, they should offer you the Everything Data 450 with a $20 recurring credit for the length of your contract, which would make it $49.99 instead of $69.99. There's a lengthy thread on the sprintusers.com SERO forums discussing plan changes.