In another thread YHFLYR said that a Viper XTX with fluids weighed 536 lbs including one gallon of fuel, on a certified Digital scale. So XF 800 at 486 lbs plus 26 lbs for E start =512 lbs, these two sleds should be within about two Super sized Big Mac Combos of each other.
Polaris uses ESTIMATED dry weight, a nice vague term.
Ski Doo for propaganda purposes is dry dry dry, no coolant about 12 to 15 lbs, no oil in chain case, no belt, no battery if required not even all that extra weight of brake fluid.