I just rebuilt my 2015 Kona Jake the Snake, moving to Gevenalle shifters with hydraulic brakes and a BURD rear derailleur with KOGEL CX pulleys.
It's not the lightest bike ever, weighing in at 21.3 pounds as pictured, but switching to the Gevenalle bits from the stock 105 drivetrain and Hayes CX Expert brakes trimmed half a pound. I raced it this morning and while it didn't magically keep me from being slow it was a blast to ride. These brakes are soooo sweet.