I actually did the math on this last night on tank fights, it was pretty fun! All numbers pertaining to hits to kill are averages, and should not be taken to be deterministic.
So let's step back and get the big picture. First thing to keep in mind is that every 100m you close, you add +1 AP to the shot. The other thing to know is that since the penetration table proceeds as a quartic function in terms of AP-AV, it's a fairly simple function so using 10AP against 5AV is the same as 15AP vs 10AV.
So, going abstract for a bit, divide the main cannon's range by 10, add that to the FAV and the given AP value, and you have a total "Tank Value (TV)." You can do the math yourself, but two tanks of equal TV, regardless of what their other stats look like, will be evenly matched. In this case, the Jumbo and Panther D wind up having equal TVs. At 1000m, both have 0% chance to penetrate. However, if you close to 500m (which is closer to historical tank engagement ranges, BTW), both have AP-AV=4, which corresponds to a 42% penetration chance, or 2.38 hits to kill. They have the same accuracy and ROF, so they're very evenly matched.
That's just comparing even tanks. If you're comparing uneven tanks at the maximum effective range, the weaker tank will take 50 hits to kill (2% penetration), while the stronger tank will take at most 12.5 (8% penetration). If you close the distance, however, the hits to kill converges. As an example: the M4A3(76)W and Jumbo cost the same, but have a difference in TV of 6. At the maximum effective range for the 76 to damage the Jumbo (600m), the 76 will, again, take 50 hits to kill the Jumbo, while the Jumbo will be at 2.38, or 21 times faster, aka the 76 will need 21x numerical superiority (ignoring the effects of morale damage, which will be substantial in such a scenario). If, however, the 76 closes to 300m, the number of hits to kill drops to 3.7, while the Jumbo's drops to 1.2, reducing the ratio to 3:1. There are two practical lessons from this demonstration: even small increases in TV can lead to massively different outcomes, and if you are using a weaker tank close the distance before engaging.
Now, on to cost. If you divide the number of points by TV, you get inverse efficiency (which is slightly more intuitive than efficiency). The average of all open beta tanks at this time is to spend 4.43 points per TV point. The Jumbo and M5A1 are significant outliers, clocking in at 3.64 and 3.75 respectively (the Jumbo is the most effective 'proper' tank - the SDKFZ 250/9 has both an AP and AV value so I put it in, and it spends 2.5 points per TV). The Panthers are also significant outliers: The Panther D at 5.71, the Panther G at 6.51, and the Bef. Panther at 6.36. In other words, the Jumbo is more efficient than the Panther family. Put more practically, you can take 3 Jumbos for 540 points, and 2 Panther Ds for 480. All else being equal, the Jumbos will defeat the Panther Ds dramatically.
However, let's consider Panther Gs vs Jumbos (TV1-TV0=1). If engagement ranges are left at max (800m) and the budget set to 560 points, 3 Jumbos will take 100 average hits (33 hit-volley-equivalents) to take out 2 Panther Gs, while the Panther Gs need 37.5 (18.75). So, advantage Panther Gs. If the Jumbos push to 300m, then they need 3.44 average hits (or 1 hit-volley-equivalent), while the Panther Gs need 4.17 (2). This ignores that Panther Gs have 7 accuracy, while the Jumbos have 5 (I don't know the accuracy tables).
MASSIVE CAVEATS
All else is never equal. For one thing, divisions have different cost incomes (which actually further distorts the Jumbo's advantage). For another, the number of tanks possible to deploy varies wildly - the 3AD can field 6 Jumbos, while the HJ can field 4 Panther Ds, 2 Bef. Panthers, and 18 Panther Gs. For yet another, none of the Jumbos are veteran.
This analysis ignores side shots, morale damage, accuracy, veteran status, leadership, etc. All of which is important.
An important thing to stress from this, however, is that higher TVs are a lot more forgiving. While the 3 Jumbos can close to 300m and defeat the 2 Panther Gs, the onus is on the 3AD player to use smoke and hedgerow hell to close that distance.
