VPS versus reseller

[nobles]

I host a handful of my own sites and a few small business sites, and my reseller account has been OK. Generally reliable, with good speed.

Soon, though, I'm going to host a half-dozen Wordpress sites for a national company. Each site will offer the company a marketing presence in a specific state where the company will have between 50 and 100 customers.

So, the traffic will still be relatively low, but I will need rock solid hosting. My client will be updating content on the sites themselves, so the WP backend must be responsive. (My current host will occasionally have some latency.)

I'm leaning toward a managed VPS such as Knownhost or Servint, which will double my hosting cost. About $50 monthly, or so.

I would appreciate any advice, particularly whether or not the added customer service and security of a higher-end managed VPS would justify the price for this scenario.