As you probably know what I am going to say, I would go with the SRAM if you can afford it. Once you have that groupset, you are basically done upgrading any of those components except maybe the crank and brakes for weight savings. With the Ultegra, if you ever want to shave weight off you will have to spend quite a bit more money to do so. Really if you spend the extra $455 now, you are probably saving yourself more if you ever consider upgrading components in the future. Does that make sense? Just get the best groupset you can afford now, then in the future you can worry about upgrading other components. Also the ~400g difference is quite a bit imho. If it was only like 100-200g then I would say maybe reconsider. Go for the Red.

Also your wheelset is quite heavy at 2245g. What are you running for wheels? In the future you would be able to shave quite a bit of weight with some new wheels. Easily 700-800g for less than $500.