[JSWolf]

ADE 2.0.1 is a good way to test that your ePub3 is backwards compatible. If it looks good enough you are good to go.

While a lot of people think ePub2 compatibility isn't important. it is. There are a lot of Sony Readers, nooks, Kobo, and others using an old version of RMSDK. If it's not backwards compatible enough, it won't work when read on these devices using RMSDK. Not everyone removes the DRM and there are those who do remove the DRM but do not remove the DRM from a library loan. As for Kobo, some do prefer reading with RMSDK because of the better typesetting. KePub has some problems when you set it for kerning and hyphenation. Plus, there is the occasional glitch with the text.