Although your idea has merit Tom, I think it's going to end up providing both sides of the coin with what they consider a substandard experience. While I think everyone can enjoy either genre of game, in an event designed for both, the skirmishers will be unimpressed by the rules, and the milsimers will be eager for more realism.
I know that eventually the IC events won't be tollerable to skirmishers at all. I wouldn't want to lower the bar just to accomodate someone who wants to play with 3 high caps.
However, Viking, although it would be super easy to do this, I would question whether it's really necessary. Most events plainly explain the rules and you can quickly gather whether it is a Milsim or skirmish event. Even now, I'm sure by just viewing the titles of the games in the events section that you could probably figure out which are which to a high degree of accuracy. Would a division really be necessary? Is there that much trouble looking through the Ontario section to find milsim events?
This could, in theory, be much easier to impliment with a simple title system rather than separate forums.
And, as a note, Newbie has a very good point, but I think it works both ways. Hosts will decide what kind of game they want, and they shouldn't be asked to compromise.