Your question is very interesting. We all have some sort of issues, some are just more obvious than others.
The PE770 is a workhorse and a machine with so many features, I think you will find it relatively easy to handle in most cases. The issue that comes to my mind is placing fabric in a hoop. The fabric needs to be taut which can be difficult for anyone.
Since your medical event is 4 years old, I suspect you have learned ways to handling things that are challenging. Here is my suggestion -
Find someone who has an embroidery machine (put an ad in the Penny Saver) and work with them on the basic things all projects require. Embroiderers are notorious for being sharing and giving people. I know someone would be happy to show you a few things.
I don't recommend going to a store to do some investigation. The reason is that the store people are often the owners and I have yet to see any of them be shy. They are very aggressive and you may find you have spent money you did not intend to. If you decide to go to an embroidery store, take a friend and have a prearranged signal to make an exit. Machine sales are much like car salespersons. Be careful. Additionally, I know of one dealer who sold the same 15 needle machine for $10,000 and up to $15,000. There is no place to determine what a machine should sell for because they are not permitted, by Brother and other makers, to give out that info. That keeps the machines artificially more costly than they should be.
Look through some blogs (like mine - http://community.anntheg...-not-really-the-alphabet - is an informative one). Ask questions, then ask more questions. There is not necessarily just one method for a situation. Pat, The Avid Embroiderer