The original Slosher is also a 2HKO. Also I wouldn't really call this one any less accurate, the main shot still goes directly forward, but the side shots are kind of random.
I'm liking this weapon. My favorite weapons are the Inkbrush Nouveau and the Jr because of their support utility, and the Tri-slosher manages to fulfill the same role while also standing out as unique. It's much more aggressive than the Nouveau since it's got more range, though not as aggressive as the Jr since it lacks the Splat Bomb. The Disrupter coupled with the Bubbler gives it some really really nice team utility, and in a way I'd say it has more utility than either the Nouveau or Jr can bring. Compared to the regular Slosher, it still performs roughly the same way in that it can hit people on the other side of walls or obstacles, and it has about the same ink coverage and about the same kill speed as far as I can tell. However, since it lacks burst bombs, and the range of the main shot is slightly botched, you'll find it harder to go for kills on distant enemies. That nerfed offensive power is made up for by its support abilities, though.
In the few matches I played with it in Turf and Splat Zone I used the disrupter as much as possible to hinder the enemy players for my teammates. I feel like I'm looking at the Disrupter in a new light kind of; when I've used it for other weapons such as the nozzlenose, it was mainly an offensive tool to aid in chasing someone down. On the slosher, I use it constantly for team utility by prodding at enemy players from far away so that my teammates can move in and splat them. It's amazing how just hitting someone with one can scare them enough to make them retreat from an advantageous position (although, if you're smart you would stay your ground and shoot). By poking at enemies with the disrupter, granting teammates a bubbler to go in with, and using my ability to splat from below walls / behind obstacles, I was able to provide a good amount of support and there was a particular splat zone match where I really helped turn it around.
For gear, I kept my Zekko Hoodie that I wear when I play the Nouveau, but Ninja Squid actually might not really be all that necessary since you aren't sneaking up on people to assassinate. My current theory is that Special Duration Up and Bomb Range Up might be the most important abilities, for me at least, because that extends the duration of your all-important bubbler and allows you to disrupt enemies from farther away. Like I said, ninja squid probably isn't a necessity for this and I might go with Recon for added team support, or just go for more SDU/BRU. Other potentially good gear abilities might be Special Saver (if you die, you lose your bubbler progress, so this is very handy and I'd shoot to have a few subs at least of this, or even prioritize it over bomb range but I wouldn't prioritize it over special duration), and Ink Recovery (The original Slosher only got 13 shots until the tank emptied, I didn't count for this one but I'm sure it's similar. So that definitely helps alleviate that, and it helps recover ink after throwing out a disrupter, which I want to be able to do as often as possible).
So yeah, I think it looks like a great support weapon and I want to use it a lot more in the future. I'm glad that people who like the bubbler support playstyle now have 3 weapons to choose from. (That said, I think you can use it in a non-supportive way, but I think it's a great support weapon!)