All three (EZ Reader Pocket Pro, Cool-er, and PRS-300) read DRM pdf and epub.
When reading ePub, the Pocket Pro normally uses the full screen for text but if you press the OK button the footer bar with the page count comes up with a menu of options. I think the other two have a footer bar all the time. See
Font Sizes on Pocket Pro for scans of the Pocket Pro with a large font on various ebook types (ePub first) and I have attached a scan of an ePub on a smaller font after the OK key has been pressed to bring up the menu and the footer bar.
The features of the PRS-300 and the Pocket Pro (Hanlin V5) are in the same table in the
E-book Reader Matrix. These are both good devices, with the Pocket Pro having more expandability and more features probably at a slightly higher price (if you get a deal on the PRS-300).