I know one person who has raced both... went from the RC8 to the Losi, but not because of differences in the cars. I've asked him your question and will post his response as soon as I get it.
I know he liked the RC8, and I also know he's pleased with the Losi... I've asked him to compare and let me know what he thinks of each, differences in performance and "behavior" on the track.
I can tell you that if you have been racing 1/10th offroad electric that either of those cars will make you happy... they're both "finesse" cars like what you are used to.