I have the RedShift stem and just installed the seatpost as well but have hardly ridden it yet.
I see you have in your wish list, more supple tires. Have you tried the Compass tires (
www.renehersecycles.com/compass-tires/)? I have the Bon Jon Pass 35mm as my rear tire and the Stampede Pass 32mm as my front and love them. This is on a 2016 Diverge Pro.