I used a similar method until I realized my data wasn't very accessible afterwards. When I needed an anual report I had to write a small script, then for taxes, then for repeating customers, and so on. I also had to go and look customer data to an old invoice and copy that when the customer repeats. All this was error prone and not architected with care.

I moved to a simple invoicing app and most of my problems were gone. I miss the command line a bit, that's all. Just my experience.