The later 109s had, among other improvements, more armor protection. Not all that much, but still did. Bomber interception became very important task for Luftwaffe planes 1943 onwards. Thus 109G-10 should be and is more durable than 109F-4 in AH.
In my experience, any cannon snapshot, from Shvak, Hispano or MG 151/20 usually does considerable damage.
If a Niki or F4U1-c pings me even once, even on slightest snapshot, I get damaged (9 out of 10 times). And rarely then it is just one part damaged. More likely it is wing + engine oil + rudder etc.
1 second burst from P 51D kills my 109 for sure. Half a second burst from Spit.
Lose a wingtip in 109 means death, I never managed to land that.
I lost parts to spraying Hogs up to d9, Nikis up to d8 and to Spit up to d11 (lost whole wing there) ! Once 109 shot my wing off at d6+.
I'd rate 109 more tough only to Spitfire and P 51D. And those did not have to bother with armor, so I think it is right.
[This message has been edited by Hristo (edited 02-27-2000).]