Not adding anything not already covered above other than opinion on productivity of a DRO. I used hand wheels on my mill for close to 30 years and put a 4-axis DRO (TPACtools.com) on it a couple of years ago. Other than marrying my wife, best move I've ever made. Maybe even on a par with our decision to start a family . . .
No worries about backlash. No counting dial turns. No doing math in my head (dial is at 0.050" and I need to move 0.023"). Absolute/Incremental indexing: Zero out on your vise jaw edge and locate the part relative to the corner. Move to the first hole (assuming things are located off from it) and zero out incrementally on it. Mine has holes on a circle, holes on a line and some crude surfacing. My shop got really cold last winter (on demand propane heat) and my DRO wouldn't display at > 20 F temps. Had a quick job to do and went back to hand wheels. It worked, but I really missed the read out. I ended up putting a heating pad on the read out to get it working.
I am much faster with the DRO. Your only regret will be you didn't add it sooner.
Bruce