I've had a Gen3 G26 since 2005. It was my daily carry gun for 6 years. A Gen3 G19 was my daily for a couple years as well.
As of last ~August, it has been my new Gen4 G26.
I have had 3 failures with it in approximately 1,222 rounds fired. That seems pretty poor to me, and is certainly a higher rate than any of my three other (all Gen3) Glocks.
HOWEVER, the three are as follows:
1) Failure to feed using a many years old, used and abuse, Korean brand knock off magazine, whose spring feels about 1/4 as powerful as a good Glock brand mag, whose follower is prone to tilt. So I'm pretty sure we can write that one off.
2) Failure to feed using a Glock magazine that I got with my first G26 in 2005, that I kept loaded for carry for all of those years, and used a bunch...and when I took the spring out the next day to replace with a new one, it was visibly shorter than the new spring. I'll call that one a tossup on what to blame.
3) A failure to eject (I think it was eject, I didn't record it well enough and have forgotten exactly what it did) using a round of Winchester Ranger, but I was using all the Winchester JHP I had up at the range because I have come to the conclusion that Winchester's quality control sucks the big one recently and couldn't trust it for defense...and as I recall the round sounded and felt weaker than the rest. Also, even though I listed this one last, it was the first to happen, on my first trip to the range, when the gun was brand new and any springs that might "break in" would not have been able to yet.
Full disclosure. ^
I haven't had any particularly problems with BTF or erratic ejection. Once in awhile I get pegged with one, I guess, but it's not common at this point. Last range trip I shot over 100 rounds and all ejected perfectly as far as I could tell.