For my purposes and skill level, weight (especially when talking about 20 or 30 pounds) is lower on the priority list for me personally than things such as reliability, price, functionality, etc. If all the other features are equal, then yes, i do start to compare weigh.
...but comparing dry weights make zero sense because you don't ride them that way so dry is not a real world comparison; it's a bench racing, paper-only comparison. Yes the manufactures can and do play games with wet and dry weights. But, just like on an adventure motorcycle, the gas/weight arguement should be based and measured solely on range. If two bikes or sleds have a range of x and one can do it with 10% or 20% less fuel, then the manufacturer (or aftermarket) has the option of putting the same size tank and getting more range or a smaller tank to get the same range. If a smaller tank, then yes, the reduced weight due to reduced fuel needed is a very real thing in the real world riding.
No less real than reducing weight with aftermarket parts. Note that the fuel weight difference goes away as the day draws to and end, but early in the day, the weight difference is there. And, for a long day, if the owners pack an extra can with 3 gallons, the more efficient sled will go a lot further on the same 3 gallons, which is also valuable.
We won't be able to compare range/gas mileage between the axys and 850etec until they are on the snow together on the same day, so we will not be able to answer that question until then.
If it turns out that one brand sled can have less fuel and less oil on board because of efficiency gains, that, to me, is valid and valuable because it gives the option of carrying less weight on a ride.
Just as valid is the weight of snow that a sled holds. Tougher to measure, though some manufactures have tried, but also very inconsistent from snow condition to snow condition. But if a manufacturer of any brand takes steps to reduce snow weight accumulation, that is valuable in the real world because a sled sitting in a show room is irrelevant to the same one at the bottom of a gulch about to sidehill through the trees.