I do know that some fixes were added late in the 3.x dev cycle. But even more memory management was done in 4.x.

One of the problems with a major release is that the Development team trys really hard to NOT break the SDK till the next major release. And I know some of these changes required a change to the SDK.So it's not always possible to dive deep into the core code to make the changes.

Does that make sense?

We continue to see products for V4 come through the submission process. Really it's the decision of the PA's to determine what to develop for. If the market demands more 4th generation content we will see more. I know some have switched to Genesis development because the process is different and in many cases faster. But as stated we see many develop for 4th gen, and why not, the content can be used for Genesis as well.