I hope module developers are testing their code under DNN 5.1 as well as 4.x and not have a "wait-till-its-officially-released-and-then-we'll-test" argument.

One of the best ways to test DNN Is by having plugins or modules run reliably inside DNN. I am sure developers will find some hard to find bugs and it would be more productive if these are discovered as early as possible and not after a release. It's beneficial for everyone, users and developers, to get DNN as stable as possible and this means involvement from everyone.   

I have seen too many "let someone else do the dirty work". IMHO, this is a little selfish behaviour. In addition,  I have asked a few module vendors about their 5.x compatibility and the answer was, they haven't tested in 5.x. yet. Well, what I will do and I am sure others will just go to the competitor who is compatible. 5,x has been released about 6 months ago. What are you waiting for? I understand that there are more 4.x out there but eventually these will be migrating to 5.x soon and I am sure new DNN users are skipping 4.x and going for the latest version.