Hi Cross
Unlike a AP shell the thicker the armour the -smaller- the hole a HEAT round makes, so at -maximum- penetration the hole is tiny and the effect becomes the same as lighting a match in the tank. Hoggs "effective" penetrations would be the thickness of armour the weapon can penetrate and still have enough punch to destroy the vehicle. Though the oft quoted maximum penetration is greater than Hoggs effective penetration, at the maximum penetration value the effect on the tanks interior becomes negligable as the HEAT round uses up all its energy 'drilling' the hole.
For example from your reference
http://www.100thww2.org/support/776tankhits.html
Note from test "e" that after the bazooka round penetrated only 50mm of armour the hole has already decreased to the size of a pencil, 1/4 inch.
Even though a bazooka or panzershreck operator may be 'feeling' tense he can still follow his training and gently squeeze the trigger to get of an 'accurate' shot. A PIAT operator can't do this he has to 'fight' the stiff trigger.
The recoil from a bazooka or panzershreck is due to the rocket exhaust hitting the protective sheild. As this cannot happen until the round is clear of the launch tube it doesnt effect accuracy. As the PIAT's heavy recoil is caused by having to overcome the bombs inertia it does affect the weapons accuracy.
The PIAT also has a much shorter 'barrel' PIAT it is in fact a spigot mortar, normally not an accurate weapon.
PIAT is mentioned as more 'effective' in your reference because it fires multiple munition types not because it is more accurate or has better penetration values.
As regards Panzershreck (in)accuraccy the same reference you quote goes on to decribe how accurrate they may have been. So juries out on that one I guess.
Also of interest,
http://www.army.mil/cmh/books/wwii/7-8/7-8_6.htm#p127
"The 1st Battalion refused to panic and set to work with bazookas against the flanks of the blinded tanks. One of the panzers was crippled, but the crew ompartment proved impervious to bazooka rounds (perhaps this was a Tiger)"
Apparently bazooka couldnt penetrate tiger side armour, this makes sense as Tiger side armour is 80cm coinciding with Ian Hoggs penetration value for bazooka.
So Ive got to say I think the current in game values look OK except for the penetration values. By all accounts Bazooka was reasonably accurate and panzershreck is after all a copy.
Best Regards Chuck.