If you ever decide to do another invite a friend weekend, it might be a good idea not to tie it to an event release like Lost Shores. I understand the intention, wow new players with new content, but in practice there are, IMO, some issues with it.
Existing players are going to want to do the new event content. Obviously. But new players are just going to be trying to get the hang of the game. Even with level up scaling, you’re just putting new players into high skill situations (using characters with few skills/traits unlocked). Especially the final event, where even experienced and high level players were getting killed repeatedly in large numbers. Something which would likely frustrate new players, who would probably be better off in the entry zones.
Also any bugs in the new, untested content, could turn off new players as well. Even delayed content (as I saw with Lost Shores Phase 2 opening event) can be a problem, as new players want to be doing something, not waiting in Lions Arch for something to happen.
Any future events tied to an invite a friend trial should be tailored to those players. For example, instanced content (in low level zones)—very similar to person storyline quests—that existing players and their friends can participate in together. It would offer the opportunity to create new, interesting content that could still be tailored to low level, inexperienced characters.
Just my personal thoughts. Keep up the good work.