I would probably use the 180x for general work, and move to the 350x for finishing cuts.
I've got a 220x, and if/when I get another will probably go finer. If I ever have to do serious regrinding on something, I'd probably put a white wheel back on. Some have said a 220x is too slow for everyday work, but my theory is if it is slower, I'm less likely to screw something up, and gouges will last a little longer removing slightly less with each grinding.
Thanks Tim. Definitely keeping my wheels for regrinds, big mistakes (dropping point first on concrete, etc) and such. Received some advice from others on here; will provide what I learn in a post later.

