I'm developing multiple websites for a photographer. Most of the time I build a custom design around these wonderful images the photographer makes, but in many cases the companies don't have the budget to let us build a custom designed WP site. So I'm looking for a easy way to offer my clients a 'template'. A basic website, which I setup, customize a little, as a service for our clients.
So here's my idea:
I make a theme, and every new website has its own child theme with some minor modifications. All websites are structure-wise identical, but I adjust logo's, colors, fonts and the general look-and-feel.
Each website has its own domain, so no subdomains involved.
They all share some plugins like GravityForms. This seems a mayor advantage for me: I only have to update one installation, and all clients are up to date.
Do you see any downsides, pitfalls? I want to prevent setting this whole thing up, and ending up with an unmanageable system.