We've worked on a few homes that utilized SIPS panels for the roof.
- I personally think they're great in this method as they provide a remarkable amount of insulation and create a thick thermal barrier, especially from a metal roof.
- The homes we've used them on were all flat-roofs, but I don't foresee any problems with pitched roof.
I'm not sure if using SIPS for your floor system along with radiant heating makes much sense. If you're going to use radiant heating you'd want something that would absorb the heat. Concrete is what we're used to using.
I'm sure you could get a good idea of the lifespan of a SIPS panel from a manufacturer... I don't know off the top of my head. I'd imagine it's a long time, OSB and Styrofoam will probably still be around long after you and I.
Wood stoves within log homes have been used for as long as log homes have been around. I wouldn't have any concerns with it, even liking it hot.
In my opinion, a wood stove, radiant flooring, a highly insulated home with SIPS and a good thermal mass such as a concrete floor or stone wall would be more than sufficient to keep you comfortable. A heat-pump or geothermal would just be a bonus.