yes like I said you can use both. They are both really strong.
On Jikun im using it so we dont need a healer on the second and 8 plattform so we have three of our dps with feathers to get feed buff. In terms of DPS HotW maybe a bit stronger but Jikun is a fight were you can keep you vengeance very high with two tanks during the whole fight. You can use NV more often.
On Horridon last phase, maybe i could use HotW but once the war god is dead the fight is over. Its the easiest phase imo. Our start last phase makes using HotW a bit hard to max dps.
But yes both are good now let me explain why I find NV to be much better on Iron Qon:
Once we started trying him on hc, we found the extra dmg we would gain doing the fight with 1 tank would not be that high compared to the extra dmg on the tank. So we start doing it with two tanks. keeping vengeance at a decent lvl is very easy due to the dot.
I started with HotW now like you said you can either heal or dps. Plus during the first phase its not about the group getting high dmg its more about 2-3 people getting alot of dmg. And the hardest part of the fight is the 3dog phase. There you need dps and heal. Berserk and NV are really strong, with our elemnental shaman we found it almost to be enoguh cds for the dog phase and keep the rest for smashes. And dont forget you still ahve you tranq which is more than enough to keep people alive during smash. And you will atleast have NV one more time up for one smash.
You will do more dps during the fire phase cause you are using HotW there and use HotW smash phase to heal and dps. During the last phase youz wuill probalby have 2-3 stacks so when you cast tranq the dmg you take while casting it with HotW is insane during smash.
During smash a normal tranq will heal enough to keep the raid alive. NV gives you DPS increase and heals targets that get bursted by 1-2 abilitys and keeps them alive(which happens alot during dog phase) which is the hardest part of the fight and NV is perfect for that. You can use it more frequently.
Now HotW during first phase will give you a dps increase but the dps phase is more the wind phase so it will not help as much and when you use it during the second phase you can only use it once. Now where you need dps and heal is the dog and smash phase.
During dog phase letting the co tank tank all 4 bosses and you use hotw to dps is a dps loss. Using HotW smash phase will let you take more dmg in % if you have 2-3 stacks, or you let the other tanks get more stacks so you ahve none will result in the other tank getting more dmg. Plus the extra dmg you gain while not in bear for 45seconds. A normal tranq works fine too. And you only need big cooldowns later for 3-4 smashes.
I would even say good usage with NV on iron qon(which im not doing) is about an equal increase to HotW in terms of dps.