I'm quite new to this game, so I'm doing a lot of experimentation and asking a lot of questions.

One of the things I experiment with the most is the simulator: throw random things together in battles and see what happens... study the battles round to round, so on and so forth.

Something I decided to test follows:

One full squad of explosive infantry, 10 armor / 20 range...

One full squad of concussive tanks, 4 armor / 6 range.

The battle went on for two rounds, and the infantry squad won the battle with one ranged unit remaining.

I then decided to replace, in the tank squad, one range unit with one armor unit incrementally to see what happened. Needless to say, the odds ran worse and worse for the tank squad.

But going the other way, I discovered something:

With the tank squad using 3 / 7, 2 / 8, 1 / 9, or even 0 / 10 with its armor / range setup, the battle ended in a draw (everything died on both sides) after three rounds.

So in hindsight, no matter what the heavy squad cannot win, but the infantry squad will win in more than half of the possible situations.

I'm probably wrong, but it feels like heavy units are slightly disadvantaged in general

there is a misunderstanding that tank is best dealing with infantry, however, from wat I've read, tank deal absolutely no bonus to inf.

And the good armor : range ratio for tank squads are 7/3 like always .

tank has no advantages towards other kind of chassis, and also has disadvantages towards veh, long building time, and their low number of units with their high HP make them recover slower in case of nukes and spy attack.

However, they have a very big advantages, that is exp.

Their high HP and low unit count make them harder to die, hence get more exp than the other chassis, plus they need less xp to level up. So in the long run, tank has more advantages.

So basically, if you plan your squads right and keep as many of your heavy units alive as possible for as long as possible, you'll build up a pretty tough force at no real extra cost... like workers, gold, lumber (besides travelling to attack people, but even this can be eliminated if you have your squads defending).

That would work pretty well with ranged tanks

yup, no extra cost, cuz one tank, statistically, equals to 3 inf and 1.5 veh of the same upgrade. This including damage, HP, cost and space.

And those who use tanks often use range tank as spam to rack up exp.