SurferTim,
I did some testing, this doesn't appear to be an issue for me anymore(I no longer need the EthernetServer::available edits noted previously), however I do think there could be issues depending on input and connection type. It is a matter of receiving the request as soon as possible and responding to each of those requests a little bit at a time. By responding to each request a little bit at a time it allows the server to be more responsive.
Thanks,
-diesel