SRAM Drop bar to MTB hydraulic brake interoperability

I was very interested in this question, because I have a set of Apex road brakes (levers & calipers) mismatched with one flat mount and one post mount. As noone has provided a satisfactory answer, I thought I'd do it myself.

For my new frame, I need post mount brakes, but the HRD calipers are rather hard to find and expensive. Also I have a set of Avid Juicy 3 brakes sitting around, one fine, the other seized.

At a glance, and without taking any measurements, the Juicy caliper looks very similar to the Apex Post Mount caliper with a very similar size and shape body, similar pad area and very similar piston diameter, so I hooked up the front of the bike with the standard Apex setup and the rear of the bike with the Juicy caliper. The brakes feel similar to each other at the lever, enough to say there's no difference. The Juicy caliper works very nicely though does provide a little extra braking power. In my opinion, the SRAM road disc brakes are a bit weak, so this is welcome. I doubt there will be longer term problems but I will update with how things go as the (new) pads wear down.