If you're lucky enough to find a financial and administrative all-rounder than definitely go for it! But...they're pretty rare and especially on the bookkeeping front you want to make sure you've got the best possible expertise.

I've been an (interim) CFO (that included doing all the bookkeeping) of a startup for 2 years even though my financial skills aren't superstrong. We managed to make this work by:
- making sure the financial processes were as automated as possible
- our accounting tool was easy to use and linked to our other tools
- having an amazingly skilled and flexible accountant on speeddial. I could literally contact him on Skype chat at any time if I needed help.

This could also be a potential solution for you. If not, I would suggest choosing 2 separate people whereby you should NOT save money on the bookkeeper as it is so incredibly important.

All the best and let me know if I can help you with some more insights!