I have size 9 boots (rome) I have S/M 390boss and L/XL 390's from '09.
Bought the Boss to get a better fit for my boot. I must say the S/M fit much better but the toe strap is almost too short.
But the fit for the boot is so much better that it's worth the toe strap being a little short imo.
I wear 9.5 Nike ZF1. I just bought a pair of 2010/2011 L/XL Rome Targas and they seem to fit a bit large on my boots but a bit of tweaking can get them dialed in solidly. I haven't been able to ride them unfortunately since the aeason is done on the East coast (maybe I should drive up to JP? haha).
I'd say the the S/M would be a pretty dead on fit for an 8.0 boot. You have the adjustibility of the Targa and once they pack out a bit, they should be just perfect. Lucky boot size you have for Rome bindings.
Sweet thanks for the heads up i actually picked some up today and have been messing around with them and trying to get them dialed in they can be tough to work with but they are really sick. Just need it to be next season