From: Leeuwarden, Netherlands
Me I don't look at numbers, I look at where is what. And maybe most important; the green bar, you can read that as "will to fight".
With "where is what" I mean the right equipment in the right environment can be hard to beat.
Inf in the open with no AT gun/armourprotection? Dead meat for your panzers or Artillery. Enemy armour in hills and woods with no Inf. protection? Dead meat for your AT troops. No matter how large your opponent's force is, the moment you see its green bars decreasing (because of bombardment or lack of supplies) he will be ripe for the plucking.
So vice versa, Inf holed up in hills/forests with their "health" bars at max, can be hard to beat in a direct assault. It can be done if you outnumber him though, like Kraftwerk says, say 3-6 times is a good guess. I'd rather encircle such a well dug in unit, then bomb the sh*t out of him, rinse and repeat a few times, then he's yours without taking too many casualties yourself.
To give an example; say four tanks (so no tankriders or recon cars included) face 40 Inf (no AT guns there); the tanks will most likely kill most of the Inf, say 20-25 before running out of actionpoints. Now when those tanks face that same unit in a forest, most likely 2 tanks will blow up for the loss of 15-20 Inf.
Now placing those four tanks against that same fourty Inf in the open, but give that tank unit some armoured cars, so 4 tanks and 4-6 recon cars, will most likele result in the destruction of that Inf. unit.
Again placing that fourty Inf unit in a forest but now with 4 AT guns and some bazookas will result in the loss of 2-3 tanks and 2-3 recon cars before the rounds end.
So no number crunching on my side, cause I hate that ,but more "what feels right"... well sort of.