Name the features you are talking about that get lost in your opinion. .azw3 (.kf8) has brought less new stuff to the "playing field" than you might expect.
And as .css formating conventions go - it was mostly hit and miss anyhow. You can argue, that once people accepted azw3 as the new default, they optimized their .css sheets for it - but thats all minor stuff in comparison (think floating text around objects, marginally better alignment options for some objects, stuff like that).
But lets not draw this out beyond its purpose here...
Look at both, decide for yourself. The usage with JBPatch is a fringe case anyhow.
(And in the end you almost always want hyphenation - so...)
For me its more about the story behind it (azw3 (kf8) by no means was that much better "featurewise" - it mostly served another purpose...
).
If the ePub 3.0 featureset became more widely used, the story might have been different.