I've had three trailers with "walk on roofs" all three had some give between the rafters. (I'm 215 lbs.) The newest one a 35 ft. TT is the softest so far. The first two were toy haulers which tend to be a little beefier. As for the cut roof only you can decide if you can live with it. Most used units have no warranty at all. If it were me and everything else was right on the unit I would ask them to repair and warranty the item for 6-12 months. If they are confident the roof is good they should work with you.