Huh? I've been called a regstar by every salty imp player in existence on this server and I have never seen Symphony of the Forsaken and AV ( An Vod'ika ) in regs or ranked ever. Or if I have, those players must have been complete nonfactors and therefore never show up on my radar. US has been dead since ages ago.
In any case, Imp side still has the advantage. Only a very specific selection of players from WAI and a tiny handful of assorted other pub players can compete with LD50 and Resurgum which generally possess the strongest pvpers on this server. Add to the fact that the average pug on imp side > average pug on pub side = uphill battle for pubs. Advantage for imps yes, but not totally lopsided or dominant as some would leave you to believe.