I understand your question -- I have seen an evolution in many engravers and an increasing number of jewelers are forgoing the magnification lenses (there are many varieties that have been used historically) for the better magnification and optics of microscopes.
i have used the telescopic style, as well as the galilean type. both types were optically reasonably good. i could never get used to the difference they provided. it was kind of weird getting used to them. i ended up selling them off. ymmd
A few years ago I bought a set of Zeiss "dentist loupes" figuring I could engrave barrels and other large objects instead of trying to fit them under my microscope. I found out pretty fast that I shouldn't have gotten them in 6 power. It was impossible to stay focused because of the narrow depth of field and experienced the same head/neck aches that JJ did. I sold them on eBay at a significant loss. Another valuable lesson learned.
A few years ago i used magnifying googles from Obrira with a 2,3x magnification. Like with a microscope you have a fixed distance of how far your eyes can be away from your workpiece. It was around 30cm. The depth of field depends on the magnification. As higher the magnification the shallower is the depth of field. So you have to hold your head stiff in the exact position. Moving your head slightly back or forward moves also what you see in focus. It worked well as long as i could work with them. After a while i got severe neck issues.
Now i work with a microscope and i dont have any plans to go back to the googles. It is a much better way to work in an upright position instead of bending your head over the workpiece.
With other words, just because one uses a microscope does not necessarily mean you need or use highest magnification. There is also a big benefit in ergonomical working that comes with the microscope.
At the dentist a couple years ago I tried on the hygienist's magnifiers. It seems they were about 3x, with a decent depth of field. Their main advantage over an Optivisor might be the longer working distance, which was probably 10"-12". I can't remember the mfr, but they were pro grade and she said they were about $800.
I purchased a microscope for detail work on sporting arms for engraving animals & birds, I'll still use my optivisor.Here's a company I purchase my optivisors from eHobbyTools.com there very light on your head and a good choice of lenes's J.J.
Hi Dave ,l have purchased almost every variety out there from the cheapest to a couple hundred dollars. There is a pair that are well over a thousand but l'm not that nuts. The more expensive ones are good as far as magnificatuon, The problem l personally have with All of them is that the minute you move your head anywhere you need to refocus and stay in that position the whole time. Found that l waste alot of time that way plus it breaks the groove l'm in while working on a piece. With The microscope everything is set. Move your head to do anything put it back on the microscope eyepieces and your back to work instantly. Some it seems feel the glasses are the only way to go and l guess whatever floats your boat. The vast majority use a microscope.good luck in your journey.
I use a microscope for engraving and the Zeiss loupes for the hobby dentistry I do. I don't have a license or diploma but I've watched a lot of Youtube videos and I have to say I'm pretty darn good at it. I just wish I could get that stuff that makes patient's mouths go numb.