I may be new here, but a few years back, I had my own website on which I posted my own work and the works of friends. I found that running a serial encouraged repeat visits - and a LOT of comments and feedback. No one ever wanted to know if the story was complete before it was posted, they just wanted to know what was coming next.

In a site such as this, where there is so much work, I can see where that would be a problem. As much as serials are appealing, the quantity of work here dampens the impact.
I vote for complete stories.

As to length, well, I've always been told that in matters of sex, bigger is better ... Seriously, as a writer, I do not concern myself with length. As a reader, I seek quality, not quantity.