WPMU Accont on customers' sites

Ok, don't know if I'm doing something wrong, but when I install a WPMU plugin on a customer site (via WPMU Dashboard plugin), I'm forced to create a separate admin user in order to protect direct access to my WPMU Dev Account.
Moreover (but tell me if I'm wrong) my customer can't update plugins unless he logs in as me.

Also, if I remove wpmu dashboard plugin, I keep getting a boring message on top of page.

Am I using the right practice? Is there a way to let other admins update plugins (as long as my account is valid, needless to say) without accessing my personal data?

Thank you