Man, I hate to see it when the HKs don't run right.
As a sub-compact, it is going to be a compromise over the operating systems of the full-sized models, and consequently, potentially less reliable.
I would not recommend the LEM trigger, I love my DA/SA P2000.
That sort of malfunction would normally be the result of inadequate mag spring pressure or the slide moving too fast. Do you have any full length USP Compact or P2000 mags to try? You might see if Wolff makes the springs for those mags and complementary recoil springs. I doubt if HK will be much help, but you could contact them and see.
If I were you, I would not carry the Speers until I had sorted the problem out, and would not carry that pistol with the Rangers either, unless I had put at least 100 rounds of them through the weapon and your carry mags without a stoppage.
Best of luck.
TR