rpenmanparker 

Funny thing is this is the same "upgrade" other folks contemplate right on the day they buy the bike. Should I buy the 2014 with 5700 on closeout or the 2015 with 5800 for regular price? Should I get the deal on the 2014 and then do the upgrade myself cheaper than the price difference for the two different year models? And also what is the best upgrade I can make to my bike, wheels? The answers to those questions are seldom as conservative as the answers posted by many of you here. OP can't be more than a few months away from this question except he already owns the bike. He bought his bike on the cusp of the changeover from 10-speed to 11-speed, but landed on the "old" side. Especially since he want the newer, much better wheels and if he plans to keep the bike a long time, but even if not, why not get on the "new" side of that divide for peanuts. 5700 will still work great for a long time, but 5800 will be up-to-date for some time going forward.

About the crank, FSA Gossamer is a popular OEM choice for new bikes, but very few folks think it looks as good or shifts as well as the 105 crank.