HCM touched on this, but our agency has been drinking the .40 kool aid since 1996.
The ideal was, they (INS/Border Patrol) loved their .357 mag, 158grn at 1150fps. It was proven for decades. So the closest ballistic duplication they could find was .40, 155grn at 1150-1200fps. Pretty much identical on paper. But, the round beat the shit out of our first gun, the 96D. They ran, but they are locking blocks and frame cracks were not unheard of.
Time and testing of tens of thousands of pistols in inventory have shown the USPc, P2000, and 229 as running pretty damn well long term with relatively hot .40 ammo. Far better long term than the 96.
I would say that CBP and BP combined account for close to 40,000 of the HK compacts. And well over a decade has shown them to run, and run well.
I am not a huge fan of the pistol. Not an LEM fan, and not a paddle mag release fan. But they run, the mags are great, and my super corrosive sweat never left a spec of rust on my HK or the mags.
As for the 229, I have yet to see a cracked frame. We had one pistol nation wide crack the nose end of the slide off where the recoil spring seats. We installed fresh recoil springs and drove on with no issues. I have to do office wide pistol inspections annually and have only seen two 229s with rust issues. Overall, they have help up well to the .40, but are gettin a bit long in the tooth at 12 years old...
We will be a 9mm only agency in the next year or so. .38 will soon be gone, and .40 will be phased out as we issue new 9s and burn up the last of the .40 ammo inventory...