Well, interstingly enough, when I renamed the Sony Reader dir on my SD card, that enabled me to read Edward.Gibson-The.Decline.and.Fall.of.the.Roman.Empire.txt @ 9.1M Now, the other, Albersons-blah.blah.blah@ 5.9M cannot be read. The only difference between the two is that one is ASCII and the other is ISO-8859.
Edward.Gibbon-History.Of.The.Decline.And.Fall.Of.The.Roman.Empir e.txt: ASCII English text, with very long lines
Alberts-Molecular.Biology.Of.The.Cell.4th.Ed.txt: ISO-8859 English text, with very long lines
So, I'm going to convert the iso-8859 to ASCII and see if I get a better result, I'll post the commands I use (I am a full time linux user so everything I do is geared towards that, I use .txt files primarily obtained from pdftotext. So, minor mystery, I'll post updates)