In case you ask me, I think all this additional units should be Techs, or Weapons developments, and because of that, they should be stronger and better than the units they replace, or else it would make nonsense to buy them. If the old 75 mm horse drawn artillery have the same combat value as a self propelled 155 mm artillery, then why botther ?
Self propelled artillery cost 6 IPC, A2, D2 and boost 2 matching infantry units.
It can boost 2 other units because it has better mobility than the horse drawn artillery. I am by far not as good in math as Baron, but I figure a buy of 12 IPC (1 S.P Art + 2 inf) gives you 6 pips in attack. That is as strong as 2 Tanks, but you get more fodder. That makes sense.
Now, if the S.P. Art should cost 5 and only boost 1 inf, that is 8 IPC, or 9 if the inf is a Mech, but you only got 4 pips. That is the same combat value as the old art/inf combo, only more expensive, hardly what I call an improvement, or battlefield game changer.
I think the Heavy Tank should cost 8 IPC, A3, D3 but absorb 1 hit, as in the A&A 1914 rules, or take 2 hits to kill, like a Battleship on land. I dont know what is best. But I do know that the Heavy tank was a hard target, not a push over. When you pay for extra panzer and protection you get a Blockhouse on wheels, and that should not be easy to kill. The light Tank was easy to kill, not the King Tiger. I think all Tanks should A3 D3 because even if the guns were bigger and giving stronger firepower, the Heavis lost a lot all round combat effectivness in mobility, because of the weight. The Heavis never made the same shock wave as the medium Tanks, because they were too slow. But, of course, all Tank types should be able to boost the Tac and Blitz.
Tank Destroyers are intriguing, is it a Tank or an artillery ?
Cost 5, A2, D3 seems legit. But, should they have the ability to target enemy tanks ? Like the AA gun target aircrafts ? I dont see any rational point in spending a lot of extra dollars in a Tank killer that kills a lot of cheap infantry fodder, while the enemy Tanks survive like they usually do, with or without any Tank destroyers present.
Maybe if defending Tank destroyers fire a preemptive shot at attacking Tanks ? But then we get the issues with sequenced fire resolving, making attacking Tanks obsolete.
Another take is to lets say, if a Tank destroyer rolls a 1, an enemy Tank have to take that hit ?
I dunno, man