They’ve been great the entire time. I really don’t know how a company could stand behind their product more than Glock has for me.You got a lemon, you got explanations that are head-scratchers, and have had some gun problems. But I think your attitude is spot on. Glock paid to try to resolve. Listened to your perspective. Paid for shipping, replaced the guns, and made up for a mistake (keeping your night sights) by sending some new ones to you. I'd say you had a lemon, followed by a good "honest effort" attempt to resolve, and a good level of customer support. Not perfect, but the end result was a good path for you.
Good for Glock for setting you back on the right path. Hopefully you love your new gun(s)! Good luck!