We live in a split level, manufactured home (came down the road in 2 pieces). The "seam" where the house pieces are joined runs the full length of the house (we have studs, sheetrock walls, etc. so it is a real house). However, we have found that as the house settles, the two halves are not settling at the same rate and we have cracks in the sheetrock and the foundation (full concrete with a basement). The Canadian company who manufactured the home is out of business (of course), and seeing as it was built in 1983, we have no true recourse except paying for any repairs ourselves. The only other "complaint" I have (and it isn't really a complaint) is when we were renovating, we found the floor and ceiling joists run opposite (90 degrees) from a regular stick built home! Don't know the reason why (a Canadian building code perhaps?), but once we figured this out, renovations became easy. All in all, I wouldn't hesitate to buy another manufactured home.
We actually also own a mobile home (came in on wheels in one piece way back in 1973!) and they are constructed very differently from manufactured or modular homes.
Good luck with your decision!