Thank you to everyone who has worked on Sigil. The more time I spend with it the more impressed and grateful I am for this wonderful program.
I have been slowly figuring out ePub3 (yes, slow learner here

) and finally feel comfortable adopting it with all my ebooks going forward.
What I'm trying to decide now is:
Should I use this nifty ePub3-itizer plug-in to go back through my entire ebook library and convert all the ePub2s into ePub3? What are the advantages to doing this? Any disadvantages (other than the considerable time it will take)? Do you foresee a time when ePub2 will no longer be readable?
Muchas gracias for any thoughts