I just got the same notice here as well with the May 21st deadline. From what I've read on Ecommercebytes eBay is attempting to move ALL sellers to managed payments before the end of the year. If you do not sign up when requested you will no longer be able to sell on eBay.

I have accounts with Capital One already and it was super easy to create another separate online checking account with them. Now that it's created I can use that as my separate account just for eBay. I can then transfer funds between my Capital One accounts in seconds as needed. Plus Capital One still pays interest in all my accounts.

One other benefit is that money transfers to Capital One clear super fast, sometimes up to a week faster than transfers to my local bank account.