I've had my '06 Host Double Slide fully loaded with respect to options for 8 1/2 years. I haven't had any significant issues other than the decal in the front eventually sun damaged. I removed it and my DW painted on Host in the same place. I do have a project to replace the vinyl insert in the trim. Not a big deal, but that insert has stopped being flexible, so it needs to be replaced as it is coming out of the track. Obviously, not a problem unique to this camper.
However, every RV is individually made, so be sure to inspect that particular one.
As far as handling mountain roads is concerned, that has been a nonissue for me all over the Cascades and Northwest coasts. Mine has been over all of the mountain passes around here and on quite a few of the gravel/dire backroads through the National Forests.
I've carried it on a F350 SRW on it's maiden 1000 mile trip to Montana and back with the truck stock. Since that time, I carried it with various modifications to the SRW including 19.5s, and now I have a F450.
It could very well be heavier and taller than your Lance, so keep that in mind. However, I don't think there is "any" camper that has as much room setup in the same length. We really enjoy the large amount of floor space and kitchen counter space. Since it has some of the biggest grey/black/water holding tanks out there we've never had an issue with that.
'10 Ford F-450, 6.4, 4.30, 4x4, 14,500 GVWR, '06 Host Rainer 950 DS, Torklift Talon tiedowns, Glow Steps, and Fastguns. Bilstein 4600s, Firestone Bags, Toyo M655 Gs, Curt front hitch, Energy Suspension bump stops.
NRA Life Member, CCA Life Member