From the perspective of an owner of a 45ACP Glock used for CCW and HD, I don't view the ultra high-cap mags as a tactical advantage for routine carry or HD, but I consider them
very desirable as a last-resort stash of ready-to-use ammo for a worst case situation.
I do not view them as an advantage in a HD situation when clearing a house for intruders. In fact, the long mag protruding from the pistol can be a liability in a hand-to-hand struggle if surprised by a bad guy. It's a convenient handle that the bad guy can grab and apply leverage to control your pistol.
I much prefer a smaller spare mag for CCW and HD (carry a 13-rd 45ACP spare for CCW and grab a 17-rd spare for HD). However, we always stash several loaded
30-rd mags around the home and in each of our vehicles for use only as a last resort. My girlfriend owns the same model Glock. When we are together we can backup each other with ammo in any mag we have between the two of us in an emergency.
The ultra high-cap mags are very practical for routine use at the range. We gather them up and reload everything with FMJ before making a trip to the range. More time shooting and less time reloading on the range is a great convenience and much better use of our training time.