There is almost no dust when cutting Hardie with a Hardie blade. There are lots of chips, and safety glasses are a must!!!
Hardie does not do well when it's sitting in water. Here, it fails when installed too close to the ground, or right on top of the roof shingles. Going off memory, I think they require a 1 1/2 inch gap above shingles. I'm not sure how far it has to be above the ground. I've seen it fail when the landscaping gets above it and the Hardie is buried in dirt.
Since snow only lasts a week or so here, at the most, it's not a concern. My guess is that snow sitting against Hardie over long periods of time might allow the moisture to work its way behind the paint and eventually cause failure.
So far, I haven't seen any failure with Smart Siding. It's more work to seal it after cutting it, but it is easier to work with and the finish look is good.
I used a 3/4 inch thick, 1x4 Smart Siding trim board on my chicken nesting boxes as a lip to keep the eggs in the boxes about 7 or 8 years ago. A month ago my wife asked me to remove it so she could clean the nesting boxes better and then she used rubber dog bowls for them to next in. I was shocked at how good the unprotected Smart Siding looked. I put the finish side out, so the unfinished side was where the hens sat, pooped and made their mess. Other than a little staining, it looked prestine!!!!
