Should I be using WordPress multiuse or just different wordpress installations?

I have a few websites. I have been just uploading wordpress to those sites on my hosting account and managing them individually. But Now I have a client who i’ve put together a site for, and now manage. I would like to brand it my own, but he wants admin right to his site as well. SO… if I give him admin rights, he will ave access to all the branding options.

Should I be using wordpress MU, to better manage my sites?