Here's the first kill, an NCdot pulse laser fit Abaddon:
Here's the second kill, a Pure Blind pulse laser fit Abaddon:
Next, let's give both ships a fully-upgraded Damnation pilot to boost them, minus the Armor mindlink. That's better. OK. The first ship is now an absolute buffered monster: more than 44,000 armor HP with a good armor pilot aboard. More than 200k effective HP according to EFT. With Scorch ammo loaded, this ship does a little over 500 DPS out to 52+12 kilometers. Its resists are pretty decent, at 81/74/72/70. Its major worry is align speed, at almost 14 seconds to align and get up to warp speed.
Now let's look at the second ship. Its tank is nowhere nearly as good. 23,000 armor HP contributing to 132k effective HP. The damage is quite a bit better, though: more than 600 DPS with Scorch, and thanks to the double Tracking Computers plus the Large Energy Locus Coordinator, it can do that damage at 64+16 kilometers. Its resists are both better and worse than the first Abaddon, at 67/81/78/77. Its align and warp speed is more than a second quicker than the first Abaddon.
Why all the differences? There's a couple of schools of thought at work here. Warning: scary math follows.
The Hellcat Abaddon is currently in the midst of an evolution. The "traditional" Hellcat's low slots were two plates, two Heat Sinks, two EANMs, and a Damage Control II. Rigs were two Large Trimarks and a Large Energy Locus Coordinator (tech 2 on the last, if the pilot could manage it). This provided a sturdy all-around tank: 30,000+ armor HP providing 162k effective HP, and 81/76/72/70 resists. However, the traditional Hellcat defense has a couple of disadvantages: since it uses passive resist modules, it both requires extremely high Armor Compensation skills to be effective, and the tank cannot be overheated with the Thermodynamics skill for additional resistance. This made it vulnerable to Maelstroms and other Minmatar ships firing Republic Fleet Fusion ammunition with its heavy explosive damage.
Later PL Hellcats traded one plate and one EANM for a pair of active armor hardeners, hopefully hardeners of a type that would resist the damage from the fleet those PL Hellcats would be facing. PL would use its extensive spy network to provide that information.
The NCdot Abaddon doubles down on the traditional Hellcat, trading resistance in for an even larger buffer tank. The PB Abaddon goes in the exact opposite direction, sacrificing part of the buffer for additional resists. The active hardeners, ironically, require fewer skill points than the passive ones on the NCdot Abaddons. And those active hardeners can be overheated. Developing doctrine around these ships is to leave the active armor hardeners deactivated, but overheated, until the ship is yellow-boxed. Only then are the (overheated) modules made active. Doing so raises the resists of the ship from 67/81/78/77 to 67/86/83/82, increasing the ship to 150k+ effective HP. But that's still well below the NCdot ship's EHP. Why bother, particularly when you can only overheat for a couple of minutes?
Two reasons. First, the greater mobility helps the Abaddon in a fast-paced fleet battle, allowing it to warp off quicker, realign, and warp somewhere else. Used correctly, this can be a tremendous advantage. In fact, it was superior warp-ins that were a key factor in NCdot's success in the first R6N battle. Second and even more importantly, higher resists act as a force multiplier when you have Logistics ships on the field. Consider the resistance of the two ships to explosive damage. The NCdot Abaddon, like the traditional Hellcat, has 70% explosive resistance. To do 10,000 armor damage to this ship requires 33,333 base explosive damage. The PB Abaddon, with hardeners overheated has 82% explosive resistance. To do 10,000 armor damage here requires 55,555 base explosive damage... almost double. A single typical Guardian can add 307 armor HP to an Abaddon every second. Against explosive damage, this gives the PB Abaddon 1705 more effective HP per second, per Guardian. The NCdot Abaddon gains only 1023 per second from the same Guardian. That's 700 more HP for the PB Abaddon per Guardian every second it is under reps, making that tank much much tougher to break. That's doubly tough to do with the NCdot Abaddons, which sacrifice DPS for their larger buffers.
The NCdot Abaddon's thin resistances, therefore, were easier to crack and much harder for their own logistics to repair.
Why didn't the PB Abaddons fare better, then? Bad tactics and good spying on the part of NCdot were most of the problem. Still, a major factor for the PB Abaddons: both their weakest resistance, and the one that couldn't be overheated, was against EM damage... the exact type of damage the NCdot ships were firing with their own Abaddons.
One other question you might ask: why don't the PB Abaddons simply fit a third Trimark instead of the Energy Locus Coordinator? That would certainly make up the buffer tank difference, after all. The reason is that the 64+16 kilometer range of the PB Abaddons with Scorch ammo makes them a credible threat to Drake fleets (which typically attack from 65 kilometers or so). The NCdot Abaddons have no way to effectively combat such a Drake fleet. Ironically, the Pure Blind residents would have been better served during this fight with a fleet of such Drakes at R6N. The NC Drakes that did come into R6N came in after the Pure Blind Abaddons and Maelstroms had already been defeated.
The EM hole is a weakness that is now being addressed, and you can expect that the ideal Abaddon fitting will continue to evolve in the coming weeks and months. Of course the new fitting won't remain secret for long: military secrets in EVE are only as far away as the closest kill-board.
EDIT (7/May/2011): Follow-up on this post. Dodgy Past, a member of PL posted some interesting clarifications about the Hellcat fit, plus a link to the latest (as of May 2011) evolution of it:
NC(dot) / Ev0ke copied it off PL ( I have the original December mail ), who started using them in the Venal campaign.
The part that made it work was a T2 laser cap reduction rig which reduces cap use by 25%. The fits can be varied a bit between 1 and 2 of those rigs ( normally 2 if you expect to be doing a lot of POS / jammer shooting, 1 is enough for full combat assuming almost perfect cap skills ).
Here's a link to the latest incarnation:
The name comes from the American TV show and due to the success of the ship PL has started calling most of their current fleets 'cats'. The main DPS ship gets the name and then the assorted support ship fits get tagged with that name as well, particularly useful when you use the same support hulls with radically different fits according to the needs of a fleet.