I'm a new member/author and I posted a story yesterday (David and Jonathan).
That story is not very long (10KB) as I personally prefer them to be in the ±10/20KB range - which seems to be the opinion of the first reviewer too.
However, after reading the forums for a while I got the feeling most people prefered long stories to short ones.
I do plan to write more instalments to the story - if I get a positive feedback - and I intend them to be about the same length as the first part. The whole story could then become quite long after a while, although each part will be more like a new episode than a real 'next' chapter.
I would be interested to read what the average reader thinks and likes as far as story length is concerned.
Cheers