I usually play from 9:30ish onwards. Seems to be quite a few aussies around but yeah there's definite connectivity issues for us. It can be a real prick filling a 3v3 game - almost like the second coming of christ if you can fill a 4v4. It's not so much that there's not enough people, it's more that they can hardly ever all connect to each other.
You get things like a guy will tell his friend who he plays a lot with to come join, and the guy magically cant join for absolutely no reason at all.
I dont have much issue at all joining games, and i firmly know all my ports are forwarded properly. I suspect not everyone has their relevant ports forward. The problem with NAT is it is quite advanced to the very novice user. The game being so ridiculously reliant on that side of things being perfect makes it very difficult for a lot of people to get the simple functionality working. I mean JOINING a game in a multiplayer lobby _should_ be the easiest part of the process.