We had help from 2 of my sisters visiting at the time, so 4 of us did all the addressing by hand. It takes about 30 seconds each, and most invitations are for more than one person , so they go fast. The important thing is to have all info on your guest list complete before you start, including titles. I have done it before with others from incomplete lists, so you stop to call mom to find out a house number, or new address, it seems like forever. I by far prefer hand written. It looks personal, not like business or junk mail.
What Rebecca said. My handwriting changes up too much. One I swerve to the right, then to the left, then cursive it then something unable to read. I let the clear Avery labels with a nice font do that task. I printed enough labels to handle the envelopes for the thank you cards too.