I'm personally in-favor of no limitations. I've never played against 6 NCs in 1500 points, but I've played a number of games against 4 in 1500 and 1250 points on a 180x120cm table (I suppose this is inline with the 2 per 750pts). It simply forced me to chose AAF over other SOs to close fast, denying my Chaos fleet it's long range lance advantage. But once in so close, the IN fleet always suffers without Torps. My local IN player just gave up on the strategy when I adjusted my fleet tactics accordingly.
With terrain and thoughtful setup, how was the IN player able to even get so many shots off each turn during the game you watched? I'm also curious why it took 3 turns for the opponent to close.
Russ
Excellent question. The gaming tables at this particular place in Atlanta are glorious! Getting off subject, in this same place one of the largest 15mm-scale classical warfare battles ever played ANYWHERE was going on, with about 10,000 models or so on tables linked together the better part of 100 feet across (this is a big place). Anyway, I only caught the tail end of that battle, but I will give you an abridged BatRep of a similar situation I saw at Campaign Headquarters in Norfolk, VA, because they have really big tables at this place as well. Because of the huge tables, even with randomly rolled celestial phenomena, there were enormous fire lanes and lots of empty space. The Chaos player went first and had a lot of carriers but was not using his ships effectively, and NC guy subsequently used the first turn to move full distance to try and get into NC range (the tables are that big).
This brings up the NC nerfing. One big POSITIVE change that happened with NC's is that they now fire per-ship instead of all at once. It's important because that was a factor for this game. The first NC round actually managed to score three hits (with two crits) on a cruiser, but I admit that was just a very lucky roll. However, that freaked out the Chaos player, which the NC player used to his advantage very effectively by dropping NC markers one at a time on different cruisers, each time watching the Chaos player brace even though only one other NC shot actually scored a dead-on hit and even then only dropped BM's. For turn two the Chaos player couldn't AAF because most of the fleet was braced, but he didn't need to reload because the ordnance markers by this time weren't even halfway across the table, and the NC player ignored them despite not having ordnance superiority. teh NC player then stacked rounds sequentially, dropping them one by one on the damaged ship until it died despite being braced (it took four rounds to do this IIRC), with the last two rounds dropped on a second carrier to force it to brace even though it ended up only taking one hit.
This brings up yet another point. Like every other weapon system in the game, NC's singly or in pairs do very little, but a LOT of them are exceedingly powerful and will kill ships quickly. WB's and lances do the same thing, but only NC's are capable of this at 120cm, which is why the 3D6 scatter was introduced at range and is not being changed.
For turn three Chaos finally managed to reload two carriers, and his ordnance from Turn 1 finally reached the Imperial gun line, but once again the Chaos player didn't concentrate his ordnance (unsuccesfully trying to make the NC player brace multiple ships) so the NC player came off pretty light despite not bracing anything, though his fighters had something to do with this despite not having anything aproaching parity. Very smart fighter use by the NC player- he chopped markers out of individual waves instead of trying to wipe out one or two waves entirely, forcing all the bomb runs to be piecemeal and ineffective. The NC player once again dropped three rounds on the ship that took one hit, and that ship ended up dying despite being braced for two of the three rounds. Three more rounds were dropped on a third carrier, which ended up getting crippled despite being braced.
By turn four NC's became less effective because the Chaos player finally connected some brain cells and started using celestial phenomena to his advantage, though admittedly it was only then he was close enough to an asteroid field to use it effectively. Afterward the game was pretty normal, but the damage was already done.
I'm leaving some of the details out (mostly due to senility!), but that's the gist of the BatRep, and I've heard similar stories against players that are actualy pretty experienced. I'm going to be honest- this never came up before because in the circles I frequent, we just never mass NC's this way. Orks and Tau in particular come off badly against massed NC's, which is why these are the fleets I'll be playtesting this weekend against an NC-only fleet. I don't have enough Dominators to do it Sigoroth-style so I'll have to proxy this with Lunars and Tyrants. Tyrants in particular, since Sigoroth loves them so much!

- Nate