US Airspace System
I have just recently came from the States where I flew a scheduled cargo route, in a light aircraft (PA31) for 2 & a half years. The one big difference I found when comparing the 2 systems... is the ease at which it was to pick up IFR clearances on the go, and to get around to where you wanted to go easily & directly. This wasn't due to the popular belief that most of the country has radar coverage, in fact unlike Australia, they have quite a few mountains, which makes radar coverage impossible in a lot of built up areas. Not only that, I found that you actually had more say in where you wanted to go - even in the very densely populated areas. Although my experiences are from a light aircraft view point, I felt that the transitions from G to E to B class airspaces were really effortless. Traffic avoidance in class E airspace was routine and safe (with or without ATC help) - and most heavies had TCAS. The hardest part was after you landed, getting to your park. If these changes really do start to focus more ATC attention on runway incursions - and less on the air to air incidents, then it sounds like a good theory.