raj,
are you saying that the application layer might force the LLC to work in an ack mode, thus enabling LLC retransmissions?
Maybe I am wrong, but as far as i remember, LLC ack mode is enabled only for specific messages (flow control or signalling msg, or something like this).
For user place, LLC is always unack.
==> no llc retransmission
==> no delay due to LLC retransmission
cheers
pix