And that won't be the last time GW advertised the pack sizes incorrectly

- the Phoenixes definitely come in packs of two while the nightwings are three.
Note, the following comments are based on gut-feel rather than games.
On factions and Daemons I have mixed views. The original effect was generally to restrict people a two faction army (with undivided bits as well), the factions being chosen for the Daemons that could be used in particular circumstances. Removing the "hated factions" rule is a simplification that allows greater use of the different Daemons (quite apart from allowing more Daemon Princes). An equally simple adjustment that I would prefer would have been to require a player to choose any two of the four factions and leave it at that. I do like the different daemons as they add both colour and a little thought to the game, but can see why people might want to revert to the bland 'generic' Daemon.
Obliterators despite losing AA, are still good for 85 points as they have Fearless, invulnerable save, an extra shot and an extra FF over the terminators despite having slightly weaker FF and CC stats. So I agree about the caution on reducing their costing to 75 points.
With the significant stats reductions combined with competition for other formations in the aerospace and Titans list, 200 points for the Hell Talons feels about right. On the HellBlades, I suspect that formations of three are a bit OTT for 200 points, and worse they are similar in effect to the Hell Talons and much better than Swiftdeaths (which I presume are still in?). I would suggest 150 for two Hell Blades would be better
I understand the dilema over AA between the Desecrator and the Stalker. However I do wonder about the 4x 6+AA capability and whether that might be a little too good - why not 2x 5+AA as Hydra?