You really only have about 5 cams or so to buy that aren't inside the machine if you'd want, as the cams are all built in on the 401.
Any machine that does a zig zag stitch won't make a 'true' stitch like a straight stitch only machine like a Featherweight etc. But, you'd have to likely look with a magnifying glass to have it bother you. LOL. Straight stitch machines are the truest straight stitch because there is no wiggle room in the needle bar. The machines are typically poured castings and the needle bar offers no side to side movement. I quilt with my 401 all the time (straight stitching). And I piece with it. I don't like it for free motion quilting because of the raised feed dog plate that catches on the quilt sandwich and the tension issues due to the horizontal bobbin case. I have quite a few straight stitch only machines and I do use the 401 quite a bit.