[user38]

I have done a bit more testing with the PRST1 and Calibre. I now believe there is no limit to the number of Collections created on the PRST1 via Calibre tags. However, when I did my previous test (with 112 collections) I notices that the PRST1 would not let me create a new Collection. If you intend to manage the Collections via Calibre tags I don't see this as an issue.

One of the problems I had with the number of Collections was the PRST1 recognising the Calibre "series" metadata as Collections. I finally figured out (via this forum) that there was a problem with my PRST1 plugin setup. By default the Sony PRST1 plugin forces the Reader to recognise tags and series as Collections. You can fix this through Preferences,Advanced,Plugins,Device Interface plugins,Customise plugins. (The options allow you to create Collections from tags, series and/or authors.)

Incidentally, I noticed that when copying books to the PRST1 it creates a thumbnail of the cover. I think my issue with the transfer of metadata (taking twice as long as the transfer of the books) was with this thumbnail creation. I am currently loading 1600 books to my Reader (an overnight job). I will let you know how it turns out.