There are a few idiosyncrasies for shooting the P30/P2000 HKs. Here are a few, but I'm sure there's more.
1) Practice and muscle memory are required for your thumb to be underneath (and not on) the huge slide stop lever. Everyone is used to tiny levers from striker fired handguns that the shooter has to intentionally activate. It is very easy for the shooter to unintentionally activate the HK lever, without practice. Knowing this will save you from the follow up question, "Why does my HK not lock back on the last round?"
2) Sight picture. Sights are setup for "driving the dot," and not the "6:00 hold." This will save you from the follow up question, "Why does my HK consistently shoot low?"
3) The LEM is similar to a long, light DAO. Unlike traditional DAO's, the LEM trigger does have a "wall." Depending on the individual firearm, this may have to develop as the parts mate through use/dryfire. Part of learning the LEM is getting through the trigger take up and to the wall (staging the trigger). People do the same thing with striker fired handguns, but the take up is much shorter.
4) Keep eyes on the sights and don't look at that hammer! The shooter's eyes are going to be attracted to the moving hammer right in front of their face as the trigger is being pulled. Keep that front sight in focus.
5) Similar to #3, knowing the trigger reset location is important for the LEM follow up. The shooter shouldn't let their finger off the trigger, but keep their finger in contact with the trigger as it is released to the reset location. Then, the trigger can be staged to the wall location.
6) Magazine release. The lever release is an ambi paddle. The shooter may be faster or more comfortable using a finger instead of the thumb to release the magazine. Most people will still use their thumb, but the shooter has options for both strong hand and weak hand reloads.
7) Take the time to configure the backstrap and side panels. The user configurable grip is one of the best HK specific features. Any combination of R/L/Backstrap inserts work. A good grip fit (with muscle memory) will allow a person to (safely) point the firearm at a target with eyes closed and attain near sight alignment.
8) Have a reasonable expectation for holsters and aftermarket parts. There are many things that a person would like, but can't get for a P30.
9) It's ok if the LEM is not your thing. It takes practice because it has its' quirks and is markedly different from the ubiquitous striker fired action.
All good points.
I've been shooting/carrying a LEM for almost 10 years, over 25K rounds, and will share my experience-
1) I keep my thumb on the outside/top of my support hand. The gun locks back every time.
2) I agree on the sight picture
3) The LEM trigger is best shot at speed, driving the trigger right through the wall, like you would a DA trigger. It isn't the best slow fire target trigger, but I have learned to line up the sights and drive the trigger through the wall without upsetting the picture.
4) Agreed
5)I don't really worry about the trigger reset anymore and don't remember it ever really being a thing, but it is something that has to be learned on any pistol.
6)Thumb works for me but others may find the ambi mag release to be a nice feature for the trigger finger method.
7)Mine is stock but the panels do have their benefits.
8)All that I have changed is the front sight, a fiber optic style, on the P30. My P30sk has the factory tritium sights with the rears blacked out.
9)I find the LEM to be easier to shoot than say a striker fired Glock. The LEM is pre cooked with a much shorter wall than a Glock. If you learn to use that little extra trigger take-up to hit the wall with a little speed, you'll learn to appreciate the LEM.
As far as longevity, plastic buffers, etc., HK rates the recoil mechanism in the P30 for 25K rounds. Mine is still the original and I have had no issues. The only thing I have broken is a trigger return spring and that was around 20K rounds. It took less than 5 minutes to replace it.
The ambi slide release is probably a little loose at this point but I don't even notice it.