I started off on Devolo 14 megs - my son still uses them. I'm now on Devolo 200AV. They sync at 200 meg and I can get 50 meg out of them.
The 500 meg Powerlines might get you 90 meg downlink. Smallnetbuilder.com has done a useful review.
http://www.smallnetbuilder.com/lanwa...dapter-roundup
It's a shame that they haven't yet reviewed Devolo, which I believe sets the standard.
Hope that helps.