No no, it's a weapon ability. The BB Cannon would be stable. The other 4 weapons would be shooting at -1. There's still a trade off. I was trying to capture the fluff of the Baneblade Cannon, not the shared chassis as the cannon actually shoots self guided rockets, like an enormous bolter that gives it the fire on the move ability other imperial tanks lack.
Orton's idea about the consolidation move is interesting as well. After all, this guy is meant to take the fight to the rear as follow on units keep pushing through the gap it makes. The goal here is to get a unit that plays like the fluff and up -gunning it just makes people want to sustain and turn it into a bunker.
[geeking out warning-eject now for your own sanity]
Now to answer the question above about what makes a modern MBT designed specifically designed for breakthrough tactics is best described with the comparison of the M1 Abrams versus the IDF Merkava. The carry relatively the same equivalent armour from what's been gathered from operational uses, pretty similar weapons and apparent effective range, close to the same size / weight and similar powerplants (in HP). However, the Merkava has about 20% more operational range of an M1 due to a more efficient engine, carries more shells for it's main gun, and actually allows dismounts as every one can carry an infantry squad with them, plus uses a rear mounted turret which not to dive too much into theory basically enhances crew survivability by sticking the engine up front, etc... Basically the Merkava is designed to range farther past the front lines for longer than the M1A1 is which is more encumbered by the ability of the supply lines (generally due to the US's greater abilities for logistics than anyone else).
Now to take this back to Epic, all these (other than the infantry dismounts but BB don't have those so we can safely ignore it) really don't change the unit in the size of the battle being represented in the game. However, the fighting doesn't just stop after the end of T3. Gains are consolidated. Reserves are called up to explout the opening. The next part of the larger strategic fight starts, etc. What this means is that in the larger grand scheme of things, a breakthrough tank crew will be using aggressive forward tactics more often simply because they can run farther and longer and more independent than other units. This means they can afford to crack off a few more rounds than their contemporaries during that battle They can afford to run the unit faster / longer because they've got more range. Simply they know they can stay in the fight longer. All this meaning that they way they get used by their crews differently than say a Stormsword which even though it's based on the same chassis, due to the heavier weapon, carries less shells and doesn't need to operate forward independently so is simply used (and stated) differently.
Edit: Before L4 shows up and beats me up for blagging on the M1, I'm not. Just pointing out that the armies are designed for two different purposes

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