I do have 3 401's and while they are ok but I personally won't use them in my 600. I also have a few logictechs, a solid G, a 770... etc.

It's all personal preference but there is a performance difference.

AND, living where I do live the temperature is a factor. It can get from 90 deg in the summer to -40 in the winter. I find that the 401 can get squirelly in the cold.