Do I need a VPS?

I need to move my site to a new host (for reasons that are not particularly relevant to this question), and I'm trying to decide whether to stick with shared hosting or move to a VPS.

This is a Joomla site that does a decent amount of e-commerce via a custom web app built into the Joomla installation.  It's currently on a shared hosting plan with Rochen, and I have no complaints about the site's speed or functionality.  Maybe there are problems that I'm not aware of, but so far as I know, it's running just fine.

Yet, having discussed my dilemma with a couple of VPS web hosts, I've been told that, based upon the site's stats, I really need a VPS, and one with more than a gig of RAM.  Obviously they have an incentive to tell me this, but I don't get the impression that they're intending to mislead me.  (Of course, this could just be the sign of good salesmen!)

Here are the pertinent stats that I know of:

Hits (total, not raw)

Bandwidth

As I said, the site seems to be doing fine on shared hosting, and I'm not eager to incur the cost or added responsibility of moving to a VPS.  Based upon these stats, does it appear that there's any need to move to a VPS?

I'd be grateful for a couple of opinions on this.  Thanks very much!