Sell Older 580 EXII's for 600 EX-RT's?

[RLPhoto]

I'm considering switching out my older 580 EX II's with a set of new 600 EX-RT's. I was also considering Radio Poppers to get my 580's wireless TTL. I've seen the 600EX's for as low as 550$ on Evilbay.

Is they're a better or cheaper way to get TTL off-camera flash? I like the idea of not having to mess around with triggers but If its cheaper, Why not?

[AdamJ]

I almost feel as if questions like this are invitations for me to play my Yongnuo fanboy record one more time. 

Yongnuo YN-622C transceivers are perfect for you. They preserve all Canon wireless flash functions (both E-TTL II and manual), effectively giving your 580EX II flashes the same functionality as 600EX-RT units.

I sometimes wonder if their bargain price ($90/pair) leads people to assume there's something wrong with them. There really isn't. They do everything and, from my experience with four of them, they do it all flawlessly.

Edit: the link below is a user-written manual which is more readable than the factory instructions.

https://docs.google.com/file/d/0B77OmmGIg0gMSkJHX3RkdDJlNE0/edit?pli=1