I just returned from a 3 week working trip up in Iowa where the normal highs should have been in the 70's and lows in the upper 40's. Instead it was in the low 50's and there was frost several nights. We have all of the insulation options on our 21 and I was sure glad to have them the last several weeks.
A trailer that is used for travel will probably see a wide range of climates even within a couple of weeks. My personal feelings are that extra insulation should be a very high priority on the build sheet. And as others have said, the sound deadening is an added bonus. Also, don't forget about resale value as a lot of prospective buyers would want this option. Loren