I don't use one myself, but of course I have opinions!
First off, go electronic. Manual is good if you want to take it along with you camping or whatever, but with back issues I think it's still too much strain, it is for me anyway.
My friend who is quite tall has leg issues more than back issues but has her share of those too. She finds that cutting on her kitchen counters while standing works best for her. For me, it's not the right height, I stand table height for long cuts, and then sit for the subcuts. I change my chair height all the time depending on what I'm doing and just how is my posture that day/that hour.