Mark, I have the GRS Positioning vise. I don't use the positioning feature unless I'm using a microscope, but the vise is very stable as it weighs 42 pounds. I see it's also gone up in price since I bought mine 15 years ago! When considering the price of the vise, I'd suggest considering the cost of the work holding sets they sell as well. The pins and gadgets come in handy when holding unusual shapes.
As for powered engravers, either the Lindsay or GRS work well. I used a GRS Gravermeister for 10 yeas or so, after saying good bye to the hammer and hand graver. Recently, more or less, I bought a Lindsay palm control from one of the guys here, and absolutely love that tool!
Each have advantages over the other and each take a bit of practice to get the hang of using them. And for me, both a light years ahead of hammer and tool.
Try them if you can. Both companies make foot control models and hand control models. GRS has the self contained Gravermeister that doesn't require an air compressor.
John
Check you PM's