One of the goodies you get as a K2 supported customer is product updates. Customers without a formal support agreement miss out on this. When I was working for K2, I have supported customers with issues and the first thing I ask is what is their update level.
The general rule I follow is, if there is a product update that resolves an issue you may be reporting then you should be installing that first.
It is important that you keep your software environment up-to-date be it Windows, SharePoint, SQL or K2. However, if you are running fine without any issues then you do not need to install every product update. But keep an eye on the K2 portal and technical bulletins to stay abreast of any developments. K2underground is also a great place to hear from the global community of K2 users. There is a K2 Linkedin group and a Facebook page and for those on Twitter you should follow @K2onK2.
As K2 experts, jEyLaBs invest a lot of our time keeping up with K2 developments. We are happy to help you with any questions you may have with K2. I am currently playing with the next K2 update. Watch this space.