Abstruse higher mathematical calculations are needed!

First, calculate the difference in weight (in ounces) between cuben and silnylon tarps in the size you want.

Second, calculate the difference in price.

Third, divide the difference in price by the difference in weight to find out the price per ounce of weight saved.

If that number hasn't already made the decision for you (depends on your budget), factor in a few more subjective items: Cuben is definitely more translucent than silnylon, so it will be a lot brighter underneath when the moon shines down on you. Cuben is less resistant to punctures than silnylon, not a big deal if you watch out for snags on trees and are careful with your poles. On the other hand, cuben doesn't stretch when wet like silnylon (not a big deal for me, but mileage may vary.

I still haven't decided between my ZPacks Hexamid Twin and my older Gossamer Gear/Tarptent Squall Classic. That's because most of my trips since I bought the Hex Twin have been with grandkids using my roomier Tarptent Squall II.