Some elaboration.
I never said LEM can't be used effectively. I simply stated that MY experience -as in, just me- is that maintaining performance with it required more frequent practice FOR ME compared to legacy DA/SA systems. I could very well be the only guy on Earth with that problem and LEM pistols.
But the OP asked for background, and that's mine. I know if I want to stay "good" at running LEM I have to practice VERY frequently compared to my 92. If I went too long between live fire sessions , I'd hit the line and reliably jerk the first 15 odd shots like clockwork until I got back into the groove. So long as I didn't go too long between live fire sessions i'd be OK. But no matter how often I dry fired , the problem remained.
I gave it six months where all I fired was the P30 LEM , since the only ammo available was .40 in winter 2012 and 9mm became harder to find then the truth in Chicago City Hall. The trigger snatch dynamic never changed. I picked up the 92 after not shooting it for that long and equaled my performance with the HK. Guess it just wasn't for me.
I should stress that regardless of my experience, you need to try it out yourself. The system has solid merits as Nyeti eloquently summed up, among others. In many ways it is superior to both striker fired and DA/SA , and you'd be remiss to not at least demo it on the clock.