Forum Moderators: phranque
I imagine most people are forced to upgrade for performance as the popularity of a site (or sites) forces them to get their own server. If that's the case, you should have enough traffic to pay for the increased cost somehow.
The only disadvantages I can think of is that you may need to learn more "sys admin stuff" as you'll now be running the whole machine - but control panels make that pretty simple these days.
The biggest advantge to either a VPS or dedicated machine is you no longer have to worry aboutwhther you can or cannot do what you want. You make the rules.
Having said that the disadvantage is you get to make the rules so you have a lot to learn.