The "slashdot" effect is the main problem which will lead to VPS hosted website crashes more than any other. For example, if a VPS plan has an allocation of 2 GB of RAM and 2 CPU cores with a maximum support for around 200 simultaneous users of a complex Drupal or WordPress site, a popular social media link may temporarily increase traffic to a website 10x or 100x. In these cases, the VPS will crash... unless the overflow can be managed by burstable RAM or elastic cloud scalability. In elastic frameworks, the network monitoring software simply launches a new VPS instance with a cloned & synchronized version of the website files that can manage the additional user demand. When the traffic spikes decrease, elastic server networks can automatically scale down VPS instances to conserve resource utilization in production.
Essentially, here’s the criteria I would use to judge things – if your site is made up of primarily static, HTML-based content, then you probably don’t need a VPS package.  However, if you have a large amount of files stored, multiple sites, dynamic content, and the possibility of major traffic from time to time, then you might consider upgrading to a VPS. It’s a powerful package that allows you to do more than you could with a shared hosting plan, but requires less investment than a dedicated server.

If you are familiar with hosting control panels, shell commands, and you have basic server administration and troubleshooting skills, then unmanaged VPS is the way to go. Note that while you purchase self­ managed VPS, you should be capable of managing applications, software, services installed on your VPS. Also, you must know installation/un­installations, resource monitoring, server performance tweaking and troubleshooting of any technical issues.

Update: I finally managed to connect to the Live Chat on day 3 but my experience was horrendous, to put it mildly. I had two simple sales questions, but the operator did not have any idea what I was talking about. She was pushing me generic links, and when I asked her to consult a technician, she came back a few minutes later…asking me what my username was.

So that’s it, then – a VPS is for everything in between, right? Well, yes…and no. A VPS (Virtual Private Server) is a flexible solution that falls in between shared and dedicated hosting, not only in price but also in the way it functions. Like a dedicated server, a site hosted on a VPS gets its own RAM and disk space; however, like a shared server, it uses the same processing capacity (CPU) as a certain number of other sites. So, while your site’s performance isn’t reliant on shared RAM and disk space, it is dependent on a shared processor. Moreover, the distribution of processor share varies from provider to provider.  The table below shows how most hosting companies break down the differences between shared, VPS, and dedicated hosting plans: