I've been monitoring these sites and there are frequent service hiccups. At least once a day there is a slow/response time (>8secs), no response, high load (>20), etc. This isn't a problem with one provider, it's simply what happens when one of the sites on the same server is hacked or gets high load, or a script gets stuck in a loop, etc.
I use a VPS for my own projects, and it is clearly superior in term of performance. I'm wondering if there are hosting providers that offer virtual servers solely for web hosting? Basically, a simple setup, a bit less expensive and maybe a cPanel-style control panel. Anything out there like this?