Swap out the heavy brakes and crankset and it's really not that bad. Strongly considering Shimano again if the SRAM 11-speed stuff has reliability issues (a la force and rival 10-speed rear shifters).
Problem is 6800 is only ~$225 more so you start eating into your cost savings by upgrading parts. Also, the colors won't match between the two (6800 is a grayish color vs. black or silver on 5800.) Might be worth it to get the whole 6800 group set if weight or aesthetics is important. The new 4-arm 5800 crank is only 50g heavier than 6800. Same 50g difference between the brake calipers. I'm getting the 6800 weights from the link below. I'm already running a 6800 front brake (which I'll leave on) so I'm thinking the actual weight difference in my case will be ~230g.http://www.totalcycling.com/en/Componen ... /cc-8.aspx