We have the Mountaineer 298 which is the same floor plan as the smallest Montana 2955. It is about right for the two of us but we do look forward to trading for a larger model when we retire in a few years and can spend more time in it. We will probably upgrade to a 38' - 40' model with 4 or 5 slides. The only disadvantage to longer ones for us is it will restrict the spaces available at the local state parks that we frequent now. But I figure when we retire we will usually be staying in longer term rv parks designed for larger units.
I'm not sure of the current construction differences between Mountaineer and Montana models but usually the Monatanas are equipped with the nicer materials and features, nicer cabinets, etc. As the years go by the "standard" features on Montana's get upgraded and what was standard on a Montana last year may become standard on a Mountaineer this year. Mechanically our Mountaineer has held up well with only minor problems that we have fixed ourselves.
When we upgrade our trailer we will also upgrade trucks to a 1 ton model. I want to go to a DRW because the additional cost isn't significant and I like the additional stability and braking power. More of a personal preference than necessity, I believe any of the 1 ton models would handle any of the Montana line quite well. Good luck with your search.