John
Arranger Tracks are the same concept as Cubase's Play Order tracks and a feature I would very much like in Sonar. I don't see the similarity with the Matrix view.
Yes, it's two different approaches.
If I'm unsure of the form of the track, I would bounce the entire track to a single file, slice it to parts and load these parts to the Matrix editor. Then it will be a lot easier to toggle between different cells and decide which form (order of the parts) feels best.
If I want to try different sounds, levels, plugins, etc., then Mix Recall feature is what the doctor ordered.
For different cuts I would use different projects.
Anyway, I see no reason to toss portions of arrangement around in a separate section, as it not only clutters the workspace and waists time, but puts quite a load on system resources.
As for the Cubase style arrangement track it looks like a good and very welcome feature.