Where to start? OK, first, don’t put a 2 1/2 lb. trigger on any striker-fired EDC weapon because, if you do, you’ll only be asking for trouble.
Second, $250 dollars is a lot of money for a Glock trigger job - A whole lot of money! There’s enough information on-line (Like on this forum, itself!) for you to be able to do your own very acceptable trigger job on your own Glock. For instance, if it were my Glock I’d simply polish all the contact points along the trigger bar; and I’d change the stock connector out for an (almost) drop-in
EVO Connector from Ghost, Inc.
*
In the alternative you could get one of Ghost's drop-in
Edge Connectors along with one of Charlie Vanek's (almost) drop-in
Custom Trigger Housings with an installed trigger stop; and a set of Wolff Gunsprings, heavier, 6 lb.
Trigger and Striker Springs. This is the mechanical setup I use on two of my Glocks; and they're GTG for everyday street carry, and/or acceptable for use at many (but not all) competition pistol events.
As for staging your trigger? I usually don’t; and neither do I teach combat pistol shooting this way; but, there’s never only one way to do something right. As I’ve learned, while tapping or pulling all the way through is usually the right way to use a pistol trigger, it is not always the only way to solve a problem. With this in mind you should, nevertheless, train to either tap, or pull the trigger all the way through every time you decide to fire.
There is no acceptable excuse for, ‘letting one go’ into the ground in front of you. That’s always indicative of inadequate training, not enough practice, or an unforgivably lazy trigger finger. Until the muzzle reaches a vertical 4 - 4:30 position in front of your feet, your finger should never be inside the trigger guard. (A negligent discharge like this hasn’t happened to me, even once, with a pistol trigger in more than 50 years of shooting. Still, a 2 1/2 lb. trigger doesn’t belong on a striker-fired pistol.)
You have said, ‘
With a heavy trigger your normal reaction is to jerk the trigger, to try to make it fire quickly, which will throw off your aim; but if you pull through the slack just enough to get to the heavy, 'wall' it seems that it would never fire unless you genuinely intended, especially if you get an 8+ lb pull and from the, ‘wall'.
Not true! Only an inexperienced pistolero would say that. I think that by the time you put 4 or 5 thousand rounds through a Glock you will have an entirely different opinion. Your question has, now, run through both extremes. On the one end you’re way too light with a 2 1/2 lb. pull; and on the other end you’re way too heavy at 8 lb.
Many people I shoot with have asked me to do trigger jobs on their Glocks for them. First, they shoot one of my Glocks; and, then, they want the same trigger on their Glocks too. Know what my trigger pulls are? They range from 4.9 to 5.2 lb. There's nothing, ‘light’ about these Glock triggers - Right! The actions are mirror-polished, though; and the trigger and striker springs are heavier, rather than lighter. There’s also a mechanical setscrew stop at the end of the trigger’s travel, too.
The impression other shooters get when they fire one of my Glocks is that the trigger is smooth; and the reset is clean and sharp. Most often a Glock is (or should be) fired from the trigger’s reset position. My resets are so crisp and so clean that nobody has noticed, yet, that my trigger pulls are actually fairly heavy.
If I were to advocate one thing about Glock triggers it would be to shoot your Glock enough to become very used to the way that the trigger works, and the pistol fires. Too light a pull is bad; too heavy a pull is also bad, but for a different reason. On a Glock trigger, ‘mush’ means nothing to me. It’s strictly a characteristic of the first trigger pull; and, quite frankly, I’ve learned to rely on it being there in order to give me a little extra time to either line up the shot, or decide whether or not I really want to fire.
When I’m moving quickly I don’t even notice the so-called, ‘mush’; nor do I notice the so-called, ‘wall’. My focus is on properly gripping the pistol, and lining up the muzzle with the target. The actual trigger pull occurs very quickly, and, ‘just happens’. Tapping a combat pistol’s trigger, as well as knowing, ‘When’ to tap it, is more of a feeling in your mind than it is in your finger. Consequently, I take all of these comments about, ‘walls’ and, ‘mush’ with a proverbial grain of salt. Shoot more, and you’ll think about insignificant stuff like this a lot less.
* Minor mechanical fitting is required; so, if you go this route, pick up Ghost's reduced height
Armorer's Plate, a Glock
Armorer's Tool, and - if you don't have, or don't know how to properly use a Dremel Tool - a set of easy-to-use, EZE-Lap
Diamond Sharpening Sticks, too.