Look at the facts. Not inflation. When the 650 was introduced it was essentially the same MSRP price difference less than 850, that the 800 was the previous year.
Snowmobile.com lists the ProCross 800 at 521 lbs………Matryx 850 at 467 lbs.
Where or how these sleds are 54lbs part is beyond me.
I'm not sure where you got your numbers from but the Polaris website lists the 650 VR1 137 at 476 pounds dry. This is without electric start. Cat doesn't publish weights but at the Old Forge shootout last year the ZR6000 weighed in at 22 pounds more than the skidoo 600R 137. Skidoo lists their sled at 470 pounds dry. So taking the fluids out, the Cat would be 492 pounds dry which is less than a VR1 with comparable electric start.