If you drop in on this video at about 16 mins., it shows that the 40s have a tough time getting the main back in. The ease being slow isn't as detectible, maybe because the traveler is an option. When they let it out they need to reach slightly off while they are waiting to get the sail back in. Sometimes they pinch up to avoid the need to ease.
http://www.youtube.com/watch?v=fmpOb48Mp54
Jibing with the boom it looks like no big deal. If the main was out, then it would slam over. The wings hold the flow much better in the transitions in any case.
The force on the 72s sheet is 1 ton. Soft sail force? many times more. The force on the back beam changes too.

edit. so maybe it was the upwind foiling that he said would be hampered by a soft sail