I also gave it a try - and was rather disappointed with the new epub engine - the default layout is rather different to the previous Duokan Lite version and rather buggy. The calibre news now appear in part as mobi files with system label 'News'. An english-german stardict dictionary was automatically labelled as 'Paper' - and this system label cannot be deleted.
As the launchpad keys don't work any longer - it is no longer possible to switch rapidly between Kindle and Duokan - just for reading pdfs. This is a no-go for me at the moment. So I returned to Duokan Lite. One probably shoould wait for the next releases, when all these bugs are fixed and the launchpad keys will have been adapted.