I ended up with a Polaris pack two years ago and really like how it works for me. I only had two gripes with the pack. The probe mounted on one side but only cupped the bottom of the probe pack and not both ends. I did come off the sled and have the probe slide up and out of the sleeve so I made a cap to buckle on the top to keep it in. The other was the threading of the strap to keep the shovel blade in the exterior pouch. I tried it without strapping it in and the blade ended up coming out from me bumping the seat hump too many times. I reworked it so I have a quick buckle on the strap now so I can get the shovel in or out with my gloves still on.
As for the guys that don't want to pack all the "extra" stuff that you don't really need. I have an exercise for you on your next ride. Stop somewhere, step off your sled and walk away from it. Now picture that you are in the backcountry where the riding is good and you dumped your sled down a ravine during a good pull or ran out of gas, spare fuel jug sprung a leak sometime back and its empty, its late in the day and you have little help to get your butt or your sled out. The thought goes through your mind that you will have to spend the night out until help arrives or that you can walk out. I am making the assumption you are riding alone, but do not recommend this.
Now, take off your backpack and start rummaging through the various pockets to see what you have for shelter, heat, food/water, and dry clothes to keep you occupied for the night. Now tell me how much "extra" stuff you have in your backpack?
I won't go into details on what I carry in my pack but I know it will hold me over a night or two. I supplement extra goodies in my sled but I don't expect to rely on it if the time comes.
For simplicity sake, you may want to practice this exercise in the garage so you can equip your pack before getting out on the snow.
VB