I can kind of see the problem with mana and Im experiencing it myself as well. To be honest I did use a lot of mana before the change too, but it becomes more apparent on multiple pulls now.
Let me illustrate with an example:
lets assume 5 mobs. We start out casting one terror on each
165x5 = 825mana
we keep one mob on target and cast sublimate soul for agro, dps and heal, during entire fight we cast it 5 times
5x275 = 1375 -- 2200 total mana
on the first mob we cast shroud of nightmares because we like ac and more atk.
1x325 = 325 -- 2525 total mana
since its multiple mobs, lets assume we dont cast any spears (200 mana) or brazen bull (190). We might be using our pbae
debuff and the new veil line but the manacost here wont make a huge difference.
now on our current target we will refresh the terror as it fades, because this is the target our group assists on.
lets assume 4 more terrors cast in total (spread on all mobs).
165x4 = 660 -- 3185 total mana
So that pull just cost 3185 mana, with mana regen that means I could probably do 2 pulls before needing a medbreak, this ofcourse assumes mobs that wont die instantly, or the total manacost would be considerably less.
mana was always a bit of an issue on the sk in comparison to other classes that can tank, but with our new ability to use our other spells than terrors more frequently, and intent to do so for agro, it becomes more noticeable.
Oohh, a BIG addition, the agro on those 5 mobs after the change, is A LOT better and with A LOT less work to make it so.
That's a HUGE positive change!
Now 165 mana in comparison to say 80mana of blinding light is a bit more than the double. On the other hand it should also generate more agro, so a higher manacost is motivated. I wouldnt mind seeing the manacost reduced by say 20, but I'd rather see a change in manacost for our other spells. Sublimate soul currently costs 275mana and is on a recast timer limiting its use. Deflux has no recast timer and costs 198mana. If the manacost of primarily sublimate soul could be lowered that would be a big effect on manause during multiple mobs, blessing of althuna and malath are 130 and 150 mana taraztu's is 50, I think something in the neighborhood of 130-150 wouldn't be out of line. Cost of shroud of nightmares is also quite high for a singletarget spell, for tanks and hybrids spells usually dont cost that much unless they affect multiple targets, but as it stands at the moment that spell isnt casted that much during an ae agro / exp situation so in that regard it isnt as important.