Very interesting. Flying rams seemingly offer high probability of scoring a kill per successful interception but low probability of repeated kills per mission. They also stand a good chance of turning into suicide aircraft, whether or not they were intended as such.
I think Shamah originally envisaged his rammer as non-suicide but basically expendable, with the pilot being ejected by the shock of impact, so the maximum number of kills per rammer (never mind per mission) was one. Assuming greatest closing speed (and impact) in head-on collisions, a Shamah ram pilot who aimed to maximise probability of kill risked getting ejected into the target. No wonder Soviet propaganda called ramming "The weapon of heroes". I think all Soviet Taran fighters carried guns and weren't expendable by design, (although often expended in practice).
See Wikipedia: 'Ramming', http://en.wikipedia.org/wiki/Ramming
or James T. Quinlivan, 'The Taran: Ramming in the Soviet Air Force', RAND Paper P-7192, 1986.
As in Justo's splendid reconstruction, armouring the wing leading edges of a Spitfire would seriously reduce opportunities for mounting guns therein, (never mind what armour would do to the weight). The cost-per-fighter would be alarmingly close to the cost of the target, reducing the value of even successful interceptions. (Trading an Ohka for an aircraft-carrier might be cost-effective; trading an armoured Spitfire for a Ju 88 isn't. The Northrop XP-79B Flying Ram was designed to survive up to ten rammings per mission but this seems optimistic.) Michael Bowyer's Airfix Magazine annual article says worries were expressed even in 1939 about achieving zero distance between interceptor and target in the face of return fire. Rammers would present progressively bigger and better targets for any enemy gunners right up until the moment of collision. Guns / missiles allow safer interceptions - no standoff capability with rammers – and do better at tracking manoeuvring targets.
Japanese pilots of course sometimes rammed targets impromptu but I don't know of a well-confirmed proposal for a Japanese (suicide or otherwise) interceptor. Some sources describe a proposed Mizuno Shinryu II kamikaze interceptor variant, but this is disputed.
