Bodhi Barneywrote a review of SRAM G2 Ultimate Disc Brake on October 1, 2019
Familiarity: I've put it through the wringer
The G2 represents the latest evolution in SRAM brakes, and while this is an entirely new model it borrows a lot from the beloved Codes as well as the Guide which has been in the line for a long time. It's lightest 4 piston brake in their lineup.
Coming from Guide RSCs, there are a few standout features:
Some reviews have billed this brake as a Mini-Codes, and there certainly some similarities. To me the G2 has the same initial bite as the Code, but obviously not the same overall stopping power. This is achieved with a redesigned caliper, with a slightly narrower pad pocket. This is all leads to better lever feel, as you get more initial power and bite.
Coupled with the improved lever feel, the braking power feels more consistent all the way through from initial pad contact, to fully locked up. On long, sustained descents the G2 is less prone to fading possibly due to better heat dissipation. Especially steep rides, where you know your brakes will heat up I've noticed these maintain power better than the Guide.
Also I find that the G2 has slightly more stopping power than the Guide. So I would say a better moniker is Guide 2.0, vs Mini-code to be more indicative of the amount of power the brakes have.
In a world of ever changing standards, and proprietary parts I really appreciate the fact that you can use the existing Guide Brake pads in the G2. Which really adds piece of mind on a vacation, etc where you can walk into any shop and find in-stock replacement pads. They also offer a new organic compound, which they say isn't as quiet as the previous version of Guide pad, but in the real world I haven't noticed a difference. It also has much better wear life.
So if you're looking at a new set of Guides, change your focus to the G2. More power, better lever feel, same great modulation, all in lighter/stronger package.