I've finally got to the point of retiring my venerable PRS-505 & replacing it with a Kobo. Got the new reader yesterday - a Kobo H20. That was the only one immediately available at the W H Smiths branch I went to. (Why would anyone want to try and read a book under water??
).
I create my own epubs. Have done since I first found out that they are just slightly specialised zip files. For the Sony, there was a restriction of about 260K on the size of 'sections' of text, making it necessary to split a book into several bits, then join them together in the 'content.opf' file. My understanding was that the Sony was so short of memory that it could only make 260K's-worth available at any one time. Don't know whether that is right or not, but as explanations go, it suited me.
The Kobo comes equipped with far more memory, so I ran an experiment with an existing book, joining all five of the original the 'parts' into a single part and rebuilding the epub.
This works fine on the kobo... up to a point. It appears that page turning progressively slows down as you go through the book. Turning a page at the start of the book is practically instantaneous, but towards the end (415 pages in the case in question) moving to the next page can take up to 10 seconds.
Can anyone advise on a recommended max. size for sections of an epub? And any other ideas, etc would be more than welcome.