That is my take as well. I too live in a rural area with a limited number of machine shops that are ALWAYS busy, and the mechanics suck. So I do my own work. I also have 3 EJ engines in the build process now and others planned in the next year, so the $2k investment in mics, gauges, torque plates and other tools will be returned many fold.
But for the guy in a city with many options, who has all machining and other related work done already, who JUST needs to grind rings, and does not plan on building many engines... I would not recommend getting a torque plate. I would recommend having the rings done by the person that did the machining with a torque plate on