One shared hosting account for multiple websites?

I maintain four small websites for different projects and would like to keep them under one hosting account instead of paying for separate plans.

Hostpro.com came up while I was comparing shared hosting providers. I’m trying to work out whether a multi-site plan would be sufficient or whether keeping the sites separate is worth the extra cost.

They’re all relatively lightweight WordPress installations. Would you put them on one account, or is it better to separate them for security and resource management?