Obviously, I've spoken to a significant number of people who've transitioned from a Glock/M&P/1911/etc to the LEM. Some have switched back or moved on to something else. The following is my personal observation and is not intended to give anyone a bad case of booboo lip:
The LEM is not a SFA or SAO. Some people who come from the SFA/SAO realm expect the LEM to work the same way because it's "one consistent trigger pull every shot." But it doesn't work like an SFA or SAO trigger.
- The people who basically start from scratch and re-learn trigger control slowly with the LEM tend to love it.
- The people who stand out in class as the guys who won't slow down to practice a new technique at less than 100% speed tend to drop the LEM, sometimes after many thousands of rounds of banging their heads into the wall.
SLG and I were discussing this just last week. Some folks just won't slow down, retrace their steps, and build up new/different skills. They don't want to take two steps backward in the hope that they might get three steps forward. They're often good shooters, but they rarely achieve excellence. The unfortunate part is that they often expend the time and money and ammo to become excellent, they just aren't willing to take the humble steps necessary.
Having said that, the LEM is not some kind of universal cure for bad shooting, either. Not every human being on Earth will shoot the LEM best. Heck, there are things I do with the Glock better than I did with my P30.