Hi twinn1,
If your figures are correct which I'm sure they probably are, then on paper you would receive more rb at somewhere like Full Tilt with a headline 27% rb.
Just wanted to point out that this isn't the whole story though. You need to think carefully about what would be best for you.
Sometimes playing on a site with fishier players is more +ve than the combined effects of rb alone. Also you need to consider a software which your happy with and find easy to use, what traffic levels you can expect at your limits (ok, so this probably isn't a problem at the big rooms like Full Tilt, but you know what I mean).
Obviously the choice is yours, but you could always try out another room and benefit from the PokerStrategy first deposit bonus (if not already benefited) and see how you get on. Just a thought.
Nothing stopping you from continuing to play 888 as well as another or continuing to play the bulk of your poker on 888.
Good luck with whatever you decide, let us know how you get on.
Best regards,
Bart