Tony,
You asked if DNN Corp is concerned about upgrade stats. Indeed we are concerned about installation, upgrade, active use, and just about any other metric we can find. Related to your concern, we do upgrade testing of internal sites and customer provided sites (with customer permission, of course) looking carefully at the level of effort involved, speed of upgrade, and ultimately the success or failure of an upgrade. We also test with various 3rd party extensions from the DNN Store and would be happy to test sites from more customers and the community MVP's. It seems that we could never have enough 3rd party stuff (given DNN's extreme customizability), but we can certainly try hard.
With regard to the evolution of the Platform, we have thus far spent lots of effort on adding new capabilities like mobile and social, plus improving usability. In v7.3.0, which released last week, we also spent considerable effort on improving performance while trying to minimize the negative effects of upgrades. We found a few issues that we want to clean up with regard to upgrades (discussed in various blogs and forums), but absolutely made great progress on the performance front. Check out Bruce Chapman's recent real-world experience with his iFinity site.
http://www.dnnsoftware.com/community-...Finally, I've only been with DNN for 3 yrs so lack the lengthy history of some of my associates. However, I've seen many sites upgrade within a major version and hold back on major upgrades pending major changes to their sites. It doesn't seem that they're afraid to upgrade; rather, it's a matter of priorities and where they need to spend their valuable time. For awhile, we were even slow to upgrade our public properties because of having implemented so many custom modules. Fortunately, I'm happy to say that we got past that hurdle and now upgrade on a pretty regular basis so can take advantage of the latest content and social features. And looking at v7.3.0 with its many performance and usability improvements, we want to upgrade as quickly as possible.