You should be able to reuse it just fine.
If it is in good shape and runs well, your plumber will be
able to deinstall it and then reinstall it.
You might want to replace the drain piece so you have a new drain going into a new sink.
Those parts are readily available.

I have no expertise to answer the question that you posed. I can say that we did replace ours when we remodeled, as it was fairly old. The new one works far better, and is far, far quieter. In the overall scheme of things, we felt like we got a lot of bang for our buck out of getting a new one. FWIW.

We had to replace ours when we bought the house -- the old one passed inspection and apparently never worked after. That ws the only working part we kept from old kitchen to new one. It is one expense you don't have to add to your remodel. However, the new Insinkerator Evolution Series are so good and so much quieter, that knowing that now (we have one on the prep sink), I'd be thinking about putting a new one in.

You'll have the cost to install one anyway, and the disposals themselves aren't that expensive. Now that we've reused the old one, it would cost about as much as the new unity to have a plumber uninstall it and install a newer, quieter one. DH installed the one in our old house, but if you change sizes or shapes, you can have to relocate pipes. Some are easy to do and others are not. We're wainting until ours at least gets sick before replacing, but kind of wishin we had done it at the time.

Our old disposer was about 7 yrs old and was a mid-range model when we bought it, so it was fairly quiet and worked well. I moved it to a new prep sink and bought a new one for the main sink. I'm still happy I chose this route. If the old disposer had been much older or a small motor, low-end model, I think replacing it would have been the better choice.

Sure if it still works okay. My garbage disposal is the ONLY thing that is from my former kitchen. It's not brand new, but works fine.