It's true that it's your choice but please don't try and say because you like the feel of it that it isn't a complete waste of harmony because no matter how much wishful thinking you have it is. Math doesn't lie although feelings can. There is a reason that 99.9% of all raiding druids don't go for it. Now you may feel that you're onto something everyone else has never thought of and please don't claim here it is better without more than your personal feelings. Personal choice has nothing to do with facts.
I'm uncomfortable with low haste because I don't trust my cohealer(s) in most of the raids I bring my druid to. If I didn't feel the need to use regrowth as frequently on tanks, then I'd probably be okay with regrowth and non-rejuv instants going from 1.23s to 1.33 cast/gcd and healing for 6.3% more instead. (I have 19.83% mastery raid buffed; gaining 3619 mastery would put me at 27.35%. 127.35/119.83 ~ 1.0628).
An extra tick on swiftmend and wild growth are worth ~3% total healing. Lower GCD on non-rejuv instants and lower cast time come close to bridging the gap between that and the loss of mastery. Haste is a competitive
stat, even if it's not ideal. If 6.3% weaker constitutes "really weak hots and heals", then I am guilty as charged.
Furthermore, I NEVER said it was better for myself, let alone anybody else. I NEVER recommended it for anybody else. You attacked my choice in stat priority. I defended it. It's competitive, even if it's not ideal. I've made the personal choice to ignore the small mathematical increase in healing for the sake of comfort.
Spirit Walker's Grace does in fact fix both of those issues.
In the context of OP's raid, there is no shaman (or at least, not in the logs that were posted). SWG is not an option for him. It is far more difficult to predict where turtles will spin and rockfalls will land for 7.1s (cast time of tranq with 3043 haste), whereas it is far more reasonable to avoid them for 4.2s (cast time with SoTF).
Incarnation may be more throughput, but SoTF is more reliable
for learning the fight if there is no shaman for SWG. It may not, as you said, completely fix tranq being interrupted, but it makes it a hell of a lot easier.
I'm sorry what makes you an expert on this fight considering you've only killed it one time?
I have a feeling this is what it boils down to, though. Tonydanza and Cantbearyou both recommended SoTF before I did, and you didn't jump all over them. But a druid with an uncommon gearing choice? His opinion must not mean anything. Better try to make him look like an idiot.
So we're clear, I'm no longer a druid main (which makes me sad, because I prefer healing on it overall). I switched to my priest halfway through t14 because, well, we wanted to abuse SS on some fights and nobody else had a priest. We've had trouble keeping healers around for various reasons, but the most reliable cohealers I've had access to have been a Mistweaver and another rdruid. For what should be obvious reasons, I can't really go back to my druid fulltime now, but it's still the class that I have the most experience on and the most thorough understanding of.
I still pull my weight, too. Week 2, our rdruid was unavailable for h.jin'rokh progression. We decided that having a tranq for every other lightning storm was more valuable than having spirit shell for all of them, so I healed it on my druid in 493 ilvl. Logs here:
It says it is a normal kill, but you can clearly see damage taken from lightning diffusion and ionization.
Sure, I only have one kill of Tortos on my druid. Fine, valid point. I can't make our alt raid most of the time, but I'm familiar enough with the fight from doing it on my priest (7 normal kills, 1 heroic kill) and LFR. I've also put in my share of wipes on my druid filling in for a friend's late-night guild.
I don't think I'm unqualified to offer some amount of advice to someone who's asking advice for their first kill. Given that a lot of what I said echoed what other people said, I don't think that it was out of line, either.