To the chap who asked if 6 months was regular in the biz - Leisure currently take around 2 to 3 years to respond to slush submissions. I have heard the same of Tor.
One of the reasons to have a guy like John around is so that HE can do the polite nudging... I'd never do it myself, the logic in my head is that it just gives someone an easy excuse to reject you - writing a one line rejection is such an easy thing to do and you never know what kind of day they are having... but when your agent drops them a little nudge, well that's not so bad, because everyone expects them to be a writer's rottweiler
Good luck with the mss!