Torn about using wordpress multisite…..

I’m about to start building a variety of websites all of which will use wordpress. I need them to all be on their own domain, for example… http://www.domain1.com, http://www.domain2.com, http://www.domain3.com, and you get the idea.

My other option is setting up individual virtual servers for each wordpress site and just use regular wordpress. What I’m debating about is which option is more reliable?

Is it more reliable to have all my sites running under WP-multisite, or is it more reliable to run individual sites. Speed is a big factor, can WP-ms work well under larger loads? If I’ve got a site getting tens of thousands of visitors every day, from a speed and stability perspective will using one over the other make a big difference?

Obviously setting up new sites is going to be easier with WP-MS but I’m still torn with what option to go with. One of the sites will be ecommerce enabled, does that make a difference?

Thanks to whoever can help me work through these pros and cons.