I so far think that tanks costing 5 IPCs is very solid.
This actually makes the tank a worthwhile investment. For instance:
for 15 IPCs you can buy 5 infantry or 3 tanks. Based on average dice rolls:
5 infantry would hit 0.85 times on offense, 1.65 times on defense
3 tanks would hit 1.5 times on offense, 1.5 times on defense.
The defensive values are similar, meaning that infantry on defense is still a better investment since there are more of them, they can absorb more hits from attacking tanks! Personally all this does is take tanks and makes them a considered buy instead of the ol’ infantry only buy since tanks in older versions of the game were so neutered on defense. They are now equal value to infantry because what you are paying extra for is the increased mobility. Even looking at the numbers for if 5 infantry attack the three tanks, it is very close, with a slight advantage given to the defending tanks.
So we are still seeing that if money invested is equal, defense has an advantage as far as infantry and tanks are concerned.
Also if we increase the money to 35 IPCs and our purchases now include artillery:
5 infantry
5 Artillery (combined offensive of 3.3 hits and 3.3 hits on defense)
7 tanks 3.5 hits on offense, 3.5 on defense
If the tanks attack the infantry and artillery on average the 10 unit stack will win, with 3-4 pieces remaining.
If the infantry and artillery attack, on average they can still win with 3-4 units remaining. So artillery tip the balance of power over to infantry again with their ability to raise the infantry’s attack.
Tanks literally are costing more solely for movement capability, a tank only purchase strategy only works if you have the economy to spend more money than the other guy. If the money spent is equal, tanks still lose.