Hi
NSP GK4 and NSP GK5 are a different modules. You can use both of them at the same time. GK5 is a new generation and has a major change in it's engine but basically does the same thing as NSP GK4. The only problem You will have is that GK5 is not supported by template styling and You wll need to use a default module css and styles (configurable in external files section of a module settings.)