[GeoffR]

This is what my Glo looks like when I read epubs. Although it is patched, the patches are not needed to get the margins like this. If you wanted the bottom margin much smaller than this then you would need to patch, but if you just want to increase the top margin to make it balanced then you can do that without a patch.

There will always be some individual books that give problems. If you want perfect consistency from book to book (I do!) then there is really no choice but to edit those problem books to remove the publisher's many and varied inconsistencies.

Edit: The top page margin used here is 36px on the Glo (= 45px on the H2O), or about 12pt. Most publishers seem to use a page margin of 5pt all around or none at all.

Edit2: Although these margins can be set without a patch, the exact line spacing and font sizes I have selected are not available in the stock firmware.