A couple tangentially related thoughts....
I tend to be a husqvarna guy at home - saw, weed eater, backpack blower. I happen to have a good dealer and service facility near my house, but otherwise I'm not really brand loyal.
That being said I also do prescribed fire on the side with various fed, state and non-governmental orgs. At least in my area, almost all of those organizations are running Stihl equipment; including blowers. Backpack blowers are pretty important in the prescribed fire world for both putting in low impact containment lines (clearing debris to mineral soil) and for quickly putting in secondary containment when fire slops outside of a burn unit. All of the backpack blowers I have seen and used on burns fall into the "commercial" end of the product spectrum.
They tend to hold up to long duration usage and, arguably more importantly, move a lot more air than residential units. The key aspect of that last part is that it means a LOT LESS effort on the part of the user to clear containment lines in highly variable terrain. I'm burn in the foothills of Appalachia and while it's not the Rockies the clearing power of a commercial blower is a huge bonus hiking up and down steep lines. I would imagine that would translate well for your intended usage.
Where I'm going with this is that given your description of usage (long hours) you may want to go ahead and look at a commercial blower in your preference of brand.