I can certainly understand the problem of trying to add another format to the plugin (theoretically, my programming knowledge is mostly theoretical).
I was just thinking that a "pure" format like TXT would be relatively simple to add (compared to PDF or something that could need radical conversion). My initial thought was that the plugin could reference TXT ONLY for word count, then as I started to type that, I realized that a conversion from words to pages was already being made per some of the initial posts (x words = 1 page), so counting only words wouldn't likely be any real effort saved.
As I said, if TXT word count is not something likely to happen soon/at all, I'll just convert my TXTs to MOBIs and count them that way.