I followed once some discussion in the german Shift facebook group and I got the impression as well that the 6mq Display is more prone to break. Maybe its due to the OLED technology? In general so far, I have the feeling Fairphones are quite good in absorbing falls. Especially for the FP2 there are several anecdotes that it survived car, bus and mobile home crashes. My FP2 Fell down at least 100 times in more than 5 years and the display never broke. Also my FP3 fell down multiple times already without having a broken display.
Sure if it fells bad it can always break ,so I would def use the protective case
If you are interested in some anecdotes