WordPress MU

How many blogs should I have on one server before it pays off to move from WP to WPMU?

I currently have 3 WP blogs, all fairly small, running different plugins and with different users. It's a bit of a hassle to have to upgrade three separate WP installations when new versions come out, but nothing major.
Might bring up one or two more domains, but that's it.

Will there be any gains in migrating to WPMU over having 3-5 separate WP installations on the same host (quite powerful server with 8 cores, 16gb ram etc)

Thanks in advance for any insight!

Migrating to WPMU will have sure benefits for you... you can manage some of your all blogs setting at central place... and when the no. of blogs are less you should go ahead and switch to WPMU.

It's really a personal decision and a number of factors depend on the answer. Do you feel comfortable with the code base? Are you the only one operating the sites?

If you feel comfortable with keeping the separate installs, I'd just go that route.

Thanks for the answers. I'm the one operating all the sites yes, and I do not plan to let anyone else create a new site, but maybe my brother in law will grow into managing one at some point :-)

While I'm comfortable with keeping them separate, it's a pain to upgrade them..

Are there any performance related data available anywhere?