Secure (DRMed) MobiPocket is also supported on the Bookeen Cybook and the iRex iLiad. The Cybook probably has the best MOBI support, but the Hanlin is now "good enough" except that you can't lookup words in a dictionary while reading an ebook. See
E-book Reader Matrix and
Mobi Comparison. The iRex Iliad has a larger screen, but it is a bit slower to render a page than the devices with a 6" screen.
Page turns on the Hanlin and Cybook should be similar, and is typically quoted as about 0.9s. Most people soon get used to a page turn time of this length. If one of these devices takes much longer than 1 second per page turn then it is due to extra processing time to render the page (rather than the EInk screen and controller time). I have not noticed any such slowdown for the Hanlin on MOBIs.