Just add the effect on "track level"... but what I think would be great for the video buss is to have all the same things that are on track level like: Pan/Crop, Track Motion, blending modes all key framable?

How about it SONY

EDIT: Sorry didn't relize the effect was Motion blur you wanted - they should have that as an effect for clips.

You can nest a project with the MB you want added into another project to get what you want.
Having real MB is something I dream of. To date there's only one plugin for AE that appears to do it.
The desire for more than one video buss has been around for a long time.

Bob.

what vegas does is the exact effect I wanted. I would nest but that's slower then me rendering to a new track & then turning MB off. I was just hoping I was missing something that I've never used before.

Then it's just an effect, it's in no way real motion blur. Not that real optical MB is easy to simulate.

You can make the default one look closer by changing the type of motion blur to asymetric in the project properties.
What I've used MB for a lot is restoration. In conjunction with a mask you can work wonders with it.

Bob.

I need arm/leg blur, so it's perfect for what I need. :)

But as a general motion blur, it's not to realistic.