In my last post an Anonymous commenter suggested that I should really be comparing the Rokh to the Gallente Hyperion as they are both Tier 3 battleships and the Tier 3 battleships are designed to be more tankable than the Tier 2 ships like the Megathron. I responded that comparing a blaster battleship to another blaster battleship was a perfectly valid exercise despite the tiers.
However, I agree I should throw the Hyperion into the mix.
*Goes off and loads EFT, plays with it for a few minutes, comes back*
Ok, here is my issues with the Hyperion. Yes it has 8 turret hardpoints AND a 5% damage bonus (and 100 m3 drone bay) making it very deadly indeed. But its second bonus is to active tanking and in PvP buffer tanking tends to be a superior choice for longer survivability and avoiding cap issues.
Furthermore, the Hyperion does not have a significantly larger power grid and only 6 low slots to the 7 on the Mega making tanking an issue. Do you make use of the bonus and put on one or two Large Armour Repair mods? Or do you forsake it for a buffer tank anyways?
Well, for 8 Neutron Blaster IIs you need the Reactor Control Unit to make them fit, meaning you have 5 low slots to work with. So instead of 3 Magnetic Field Stabs you go with 2 so you can have 2 x 1600mm plates and an EANM II to boost resistances. But the lack of the third Magnetic Field Stab and the smaller drone bay now means you combined damage is less(!) than the Megathron's while your effective hit points is only slightly higher and still a lot less than the Rokh's.
You can switch to Ion Blaster IIs and exchange the Reactor Control for a third Mag Field Stab, but then your damage is only slightly higher along with a slighter higher tank, but for a ship that costs a lot more ISK. And if you go for the dual reppers active tank, you run into serious capacitor stability issues as well as the power grid issues.
In the end, had that 5th mid slot been a 7th low slot, the Hyperion would have been an obvious choice over both the Rokh and the Megathron. As it stands now, it can either tank or do lots of damage, but not both.