I have now played with the InDesign 2 30 day trial.
Conclusion: just what I was looking for.
First of all I'm familiar with the Adobe interface so that's one major bit of learning I don't have to do.
Then there's the way everything which is either impossible or incredibly frustrating in MS Publisher (such as any real sort of transparency or blending, and professional text effects (not that wordart crap)) is nice and straightforward. I especially like the way the transparency system works exactly like the one in photoshop - with an alpha blend level and then the various blend methods (standard, multiply, exclude, darken, etc etc) and that it can, so far as I can see, be applied to ANYTHING.
Also, it has some neat vector graphics tools which make doing simple but effective vector work no hassle at all.
Just for the hell of it I decided to try recreating a page out of some random magazine, and it really couldn't have been easier.