Well, I got a change to wring the G43X out along with a brand new G19.5 and my old training G19.3.
TLDR:Color me disappointed
G19.5
Good
-Ejection was extremely "robust", definitely don't have to worry about BTF.
-Magazine could be dropped without changing my grip
-Sensation of slightly less felt recoil than my G19.3
-No pulling to the left (that I sometimes get with Glock Gen 3)
-Really nice dry fire trigger, no sight disturbance at all (better than with my G19.3)
Not so good
-Accuracy for me was actually slightly worse than my old G19.3 training gun with 115gr UMC, about equal with some old mixed 115gr HP (Rem & Win), significantly worse with Speer GD 124 +P (of which I have a bunch).
-Several failures to lock back on an empty mag, not sure if it was grip related or not (was not using the Gen 5 magazine)
-Shot extremely low for me with factory sights (2" below with a dead on hold at 10 yds, I prefer 6:00)
-Actually had my first experience with "Glock Knuckle", not something I had ever experienced before with Gen 3 having owned 19,34,22,23,27,30,21 in the past.
-Surprisingly enough, I actually missed the finger grooves... A lot.
-25 yard shooting was downright embarrassing. (Maybe wrong sight picture?)
This one will be going on the trade/sale block. I will just stick with Gen3 for now. I have lots of spare parts, armorer's experience, AA Conversion, etc and my training G19 is my least accurate one. Not what I was hoping to see. I would definitely recommend someone who is getting their first G19 to go with the Gen 5 but I would not recommend someone getting rid of good shooting older Gen to "upgrade".
G43X
Good
-I love the way it feels in my hand
-I love the size and shape and weight
-First shots from a draw almost always directly on aiming point (1" dia sticky)
-25 yd slow fire was surprisingly good (almost as good as my G19.3, better on one string)
-Easier to clear holster 4:00 IWB
-Sights regulated for 6:00 hold for me with factory sights
Not so Good
-124gr +P Gold Dot (ouch, not 642 +P level of ouch but definitely 130gr FMJ ouch) I would need to find a different carry load.
-Multiple shot groups opened much more, particularly F2S drills and draw fire 3.
-Some "Glock knuckle" (not as bad as G19.5 surprisingly)
-Mag release is very stiff
-While not a significantly poorer performance than the G19.3 control, it was noticeable to me and I am not that great of a shot
-Noticeably fewer beans with a full magazine in both
I am on the fence about this one. There are things that I really like and things that I don't. Since these guns weren't vetted, I spent the whole day wearing my G19.3 in a JMCK IWB 3 (except when shooting) and it really wasn't that heavy. Using this holster there is no difference in concealability with the G43X both were basically invisible.
Like several have posted in another thread, when I pick a gun I tend to like to use that gun for everything. Changing out my CCW/House/Training guns to all G43X might not be worth the cost (trying to get rid of 60+ G19 mags is a daunting task.)
I need to think about this some more.
Maybe do some more shooting next weekend before making a firm decision. For now I am definitely sticking with my G19.3 for defensive usage.