Not so sure about that. For two basic reasons: First, rep has also brilliant players. Guys like talionis, hennessy, k'rath, obi, mitth, they can be as good as some of the best imp players. Second, some of the guys that you might think that are the best imp players also have a pub toon. I played with a Physics(one of the best pvp guilds imo) premade a few days ago, I expected to win when i saw them, but the other team had Jediyy (who also has a brilliant marauder) and Churb, and they were enough to beat our team.
There are, without question, good pubs but it seems like they havent found eachother yet or simply prefer to play with their guildies . Some of the guilds are probably good enough to put up somewhat of a fight but if the best guilds had put their 2-3 best players on one and the same team instead they'd be more competitive.
On another note, whose alt is Shaerie (assassin)? If that's not an alt I'd instantly recruit him/her for one of the better imp guilds/teams. He/she is consistently putting up good numbers, hits like a truck and isnt even particulary geared (17'ish K).