I've been comparing the Cerberus and the BB as well.
I haven't used the Berta much yet, but I used (or tried to use) the Cerberus a few times to break porcy stalemates.
Once shields are up tho it feels like trying to chew thru wood.
5k Metal happens to be the exact price of 2 Cerberus or 1 Berta.
Heres what you get for your 5k:
2x Cerberus 1x BB
HP: 7500 - 4800
DMG: 3606 - 2002
Reload Time: 10 sec - 7 sec
DPS: 360 - 286
AoE: 96 - 96
Range: 1850 - 6200
Projectile Speed: 400 - 1100
My conclusions regarding the stat differences:
HP: A clear advantage for the 2 Cerberus, however we should not forget that 1.) You just need to do 3750 dmg (i.e.: 5 Ravens, 2 Lances in a cloaking field, etc) to destroy 50% of the value of the 2 Cerberus.
2.) The BB will be built much farther back, making it a lot easier to shield from air and ground units. Actually, most of the time it will be so far back that it won't even draw fire. Even if it may be poorly protected - its so far back, you don't always have up to date scouting on that.
DPS: 2 Cerberus have 1,25x the DPS of a BB.
Range: BB has 3,3x the range of Cerberus.
In a small to midsized map it can comfortably be built in your own base.
In a large map it can be built a bit forward of your base - or perhaps at worst in the middle between the frontlines and your own base - and still reach the enemy base after smashing the enemy frontlines.
Actually why bother kill the frontlines first? Tear that base to pieces right away.
Projectile Speed: BB has 2,75x the Projectile speed of Cerberus.
If the target of the BB is not at the absolute edge of its range its shells are going to hit at about the same time as the ones from the Cerberus.
The explaination for the use of Cerberus instead of BB in Chicken seems to me: In Chicken, you want a cannon you can leave on Fire at Will with good range - but one that will not shoot the enemy spawn, as u dont want to anger the hive.
But for PVP games it seems and feels as if Cerberus could use a buff.
Either in DPS - so it becomes a bit better at beating lightly shielded targets, wrecking frontlines.
Or in Range - so it stays useful a bit longer/can be built in a safer spot.
Or by cutting DMG & Reload time in half and making it a bit more useful for crowd control at least.
A increase in AoE would have the same effect.
Even a projectile speed buff could help it catch retreating lances that became uncloaked after firing. Tho after that happens your Cerberus usually doesnt get to "Return fire" anymore.
Actually currently BB is better at this role as well, cuz apart from not being dead after lances did a hit n run on your frontline it only needs 7 seconds to fire again.