It's really difficult to know. In my experience, Hostgator might have disabled your site because the server was under load and you happened to be the highest user at the time, or your site might have genuinely been really hammering their server and require a lot of resources.
It's also difficult to know what your bottleneck is, disk IO, CPU or Bandwidth.
I would give the VPS more resources than you think it will need and then monitor it heavily. I like nixstats and they have a 14 day free trial, it might be long enough to give you peace of mind over the transition period. https://nixstats.com/
Thanks for mentioning NIXStats, you can signup with invite code BETA. Let me know if you have any feedback for status page and i'll see about implementing it :)
Here's a sample status page: https://nixstats.com/report/55243e5b4303ed7c168b4567
You can give nixstats.com a try, i've been working on it for the past year. We have a server monitoring agent that also has support for plugins (monitor nginx, apache, mysql, or create your own plugin). Here's a sample of a public status page you can create yourself. We can also monitor https/https/tcp/icmp from several locations around the world.
Free while in beta.