Two previous fifth wheels did not have dual pane windows, current one has them. We had a lot of problem with condensation previously. Now that is not an issue and the noise reduction is quite noticeable. We have had this trailer for three years and so far, no problems with the windows developing a leaking seal. Personally, we would not be without them and they are well worth the additional cost.
To help even more, I made insulated curtains for the windows. We don't use the trailer that much in cold weather, but the curtains definitely help when the temps hover around 100.