I could not wait to get my plasma cutter. After using it for different projects I see I over rated my need for it. You cannot duplicate the precision of a hand held grinder with a cut off wheel; well if you were a robot you could.
My uses for the plasma ended up being quick hack jobs mostly. It is nice to quickly cut a general shape, lop off a piece. For instance this is a gauge used to make the contour of the air dam. The inside was cut with accuracy with a grinder but the tool itself was cut out of the plate with the plasma.
You can gain some accuracy with a template and a steady hand but even then the metal still needs some clean up work. Some people like working hard to get a good plasma cut and that's good but I still prefer the grinder when i can.
I have also found the plasma useful in cutting things I could get no other tool in. I had to clear some webbing from inner body structure to make way for a bracket. No grinder or cutter would fit in where I put the plasma.
As far as grinder accuracy you might be surprised. I have no trouble holding 1/32" when cutting with a grinder and provisions can be made to be even more accurate. The 3rd image is a cam for a single cyl engine I made cut from a 1" thick plate using a hand held grinder.
Please excuse the fact I have no guard on my grinder. Yes it's a bad idea and I have no excuse for it: