Sorry to burst you bubble above though. For a 20' tree span and, say about 9' ridge line (structural or virtual), you will not be saving anywhere near what you have computed.
By the time you add up the fact that the UCR needs a much longer bury, has 2 fixed eyes instead of 1, and has 2 free tails instead of 1, the savings on rope for a UCR over the Whoopie is only about 25% (it may be less or more depending on the max desired tree span and hammock ridge line). Then add back in the rope needed for your Prussic and the savings are even less.
TeeDee and I have been around the tree many times with the UCR. By the time you add in the needed "doohickeys" like the Prussic to get the UCR to hold and not slip, your weight savings is usually very small and the amount of rope saved is very small also.
Now quite a few people here prefer the UCR over the whoopie and continue to like them for a few reasons which they have stated a few times. It's all about personal preference.