A brake's primary job is to stop, so we typically consider any technology that makes it better at that an upgrade. Shimano's Dura-Ace BR-9110 Direct Mount Brake Calipers do just that, widening the window for modulation and increasing total stopping power. Those properties amount to a great big plus in our book of braking, and the fact that they also don't add any weight by doing so adds yet another plus. In fact, they actually lose weight compared to single-bolt calipers because the direct-mount design requires less material in the brake caliper and the frame, eliminating overall weight despite the addition of a second bolt.
Tolerances are also improved all around: the caliper can sit closer to the frame and tire clearance is increased. A lower profile is especially useful in back as it lets the brake hide from the wind more effectively, but better tire clearance benefits both front and rear by accommodating the trend of growing tires. We're currently seeing 25mm as the standard, but we wouldn't be surprised if that bumped up to 28mm in the coming years.
Did you happen to replace Bontrager Speed Stop brakes with these? I'm considering doing so and interested in hearing how that goes.