For the type of family travel that you just did, the All-Packa would have been an extra hassle than what you rode. But it is doable. At the end of my recent trip, I had to

1. ride to the train station
2. put the panniers and fork bags into an Ikea bag/backpack
3. take the elevator down one level
4. carry the bike down another flight to the platform (an elevator was available but I was impatient and there were 4 other bikes waiting)
5. roll the bike onto the train
6. do a quick fold (10-20 seconds, rear triangle folds underneath main triangle, seat mast folds down, handlebar mast removed) and stowed it in the corner reserved for luggage. Coincidentally, other bikers on the trip had to remove their front wheels and hang their bikes on hooks, which took longer
7. relax on the train

And then when we arrived in New York City, I had to...

1. Unfold the bike (10 seconds)
2. Roll off the train
3. Carry up the stairs (I could have taken the elevator)
4. Leave Moynihan station
5. Rush the bike across the street to make sure I could catch the next train
6. Enter NY Penn Station
7. Take a set of escalators down one level
8. Roll through the station
9. Carry the bike down another set of narrow stairs
10. Roll onto the next train
11. Quick fold the bike (not required but it was a crowded train and I did not want to take up more space than necessary)
12. Take the train two stops.

And then there was another station with more stairs down and up and finally my home station, where I could unfold the bike on the platform, remount the panniers and bags, and ride down the accessibility ramp and ride home.

I could handle this because I was traveling solo and am fit enough to manage the carrying of the bike and an oversized backpack filled with gear. I cannot fathom doing this with a family of four!

The new Brompton G might have been better during the train part of the trip, but the Alfine-8 would not have worked out on the actual ride, where we were regularly going up 15%+ grades with loaded bikes. And my buddy, who I dubbed "Freight Train" likes chugging along flat roads at 18mph. He's in better shape than me too, so it took all I had just to sit his draft the first couple of days. I managed to take some pulls in the latter half of the trip, where the inner bar ends of the Packalope bars helped me achieve a pretty aero position and set a decent pace. I do not know yet if the Brommie G is as capable.

I do know that my Zizzo Liberte, even with its oversized 2.4" tires, would not have worked. Just not enough gearing, not enough carrying capacity, not enough speed, and simply not enough comfort for this trip. I've taken it one rides close to 30 miles, and it did the job, but I know that other bikes would have been better. It does make me wonder how much better I could make the Liberte, with better hubs, better gearing, better seat, more hand positions, etc... Hmmm....maybe a winter project...

At the end of the day, there is no single answer. We all have varying needs and requirements that changes from trip to trip even. Every gear choice we make is a compromise of competing factors. I do wish the All-Packa folded smaller and neater, but they clearly prioritized rideability, and that was key on the last trip.