So when I do this, it will now Sync as Push from MobileMe? How long does that take?
It will take a few minutes for MobileMe to download all of your contacts again. Depending on how many contacts you have and how long it's been since you "reset up to" MobileMe, it should take between 5 and 30 minutes.
And will I never have to Sync again in iTunes?
In theory, right. The only time you should have to sync with iTunes is for getting your media, photos, etc.
So this whole "circus" round-about act is going to be eliminated in the next iteration of iTunes and iPhone 3.1, right? Cos it seems downright silly that we have to do this - why doesn't it just keep it streamlined in the first place?
It really depends on your situation. I'm not sure how you ended up having both your contacts tether syncing and your MobileMe contacts being pushed to your phone, but it would stand to reason that at some point, you added your MobileMe account and decided to keep the data on your phone rather than delete it (which would have prevented this). I think it might have just been unclear or maybe a little scary?
I'm worried now that I won't have it Synced in time to get back to work. We'll see, I guess.
MobileMe push is pretty darn fast. I see my contacts sync over the air within a few minutes generally. Are you using Windows or a Mac at work? If Windows, have you already installed the MobileMe Control Panel?
But I ask again: I leave the Sync Contacts to OFF in iTunes, correct?