We had a mobile home about 20 years ago. We purchased it new, it was basic nothing fancy although we did have a natural gas furnance and central air. We sealed around all the plumbing right after setting it up on our own lot. A cemement pad would have been nice, however we used piers and also had tie downs for winds.
Our home had a pitched roof with shingles. This prevented a lot of the "sound" issues many of you have mentioned. We lived there for about 2 years and then moved. We did have heat tape on the pipes etc. and did not have any issues with freezing.
I do think the ones made in the last 20 years are better built than those from the 70's as long as you get all the gaps around the pipes closed.