Drywalling takes a lot of time, is challenging to do by yourself, and I've been told it gets old quickly. I also determined that the cost saving of me doing the work myself were not worth it in terms of the lost rental income. 

After watching the drywall crew work for the last week, I'm glad I hired this job out. 

We had to add two layers of 1/2" drywall as a 1-hour firewall between the upstairs and downstairs units. I also added green glue between the two layers of drywall to help deaden sound transfer from the upstairs to the downstairs.