I have a Kindle touch so it has been easy just grab the mobi version. But now my husband is getting a tablet for ereading. We will share some books. I gather download anything to my computer via my computer and upload using calibre to both my kindle and his tablet. But now I need to consider if continuing to download mobi versions is best. If it makes any difference the first set of books we want to both read are the double spiral wars trilogy only availiable as mobi or pdf. My daughter is reading on her galaxy and has no problems with mobi but her phone hates pdf. If that is relevant. Not sure.