Karnak,  is your judgement based on the standpoint of being shot at in one or at shooting at them?  The Mossie strikes me as being a pretty durable aircraft...at least against my six .50s.  If I can recall, it seems a big aircraft and when I do get a good sight on one, I can get a very good and long burst into the 'wooden wonder.'  But to be honest, I don't really encounter the Mossie all that often and not enough to really take away a good accounting of its durability.
Now, personal gripe is that my F4U-1 seems to lose a complete wing the majority of the time I take damage in a fight.  That just doesn't seem right and it frustrates me.