>Can someone give his/her viewpoint on the use of the CodeBehind page using versions 1.0, 1.1 and 2.0 of Visual Studio?

First I think using the code behind model is the only way to go. You loose some significant IDE features if you use the in-page model. For example I don't think "Collapse to Definitions" works in the in-page model which is a feature I use often. Plus I just think it's cleaner and easier to maintain this way.

I think 1.0 and 1.1 are basically the same in this respect although I haven't used 1.0 much. The differences between 1.1 and 2 are fairly significant. 2.0 is a slicker and easier to maintain since you don't have to declare your controls in the "partial class" model of 2.0 like you do in the 1.1 model. Although the 1.1 model still works in 2.0 if you perfer that.