New Zealand operates with a 1:50 ratio and also has an impeccable safety record.
Today, I served the flight deck and also did tea and coffee for 126 pax while my csm operated on the cart with L2 position crewmember.
We offered a hot sandwhich, saleable bar and as i mentioned tea and coffee or water, this was on a 40 minute AKL - WLG sector.
In a 3 crew operation I dont believe the cabin is any less secure than with 4, or the passengers are at any huge risk of not being able to evacuate quickly.
Our overwing pax are briefed, I (as R2) know my responsibilites and L1, L2 are aware of their door responsibilities.
I believe 1:50 is sufficient, when we did full service we operated with 4. (this is on 733/4).
Accross the tasman we operate the 300 with 4 and the 400 with 4 up to a certain number of pax and 5 when the pax goes over 11/100 as an assist.
Be interesting to see when this is implemeneted. . .