There is one definite difference between the 2, and that's the vortex always dealing 38.0 damage whereas in Splatoon 1 the outer vortex dealt a considerable amount of less damage than the inner vortex (which is closer to the actual shot). It's the same changes seen on the Blasters and Bombs, the non-direct damage is a constant number regardless of distance from the explosion, so Rapid always deals 35.0 on indirects, even if the shot was at the maximum range of the explosion damage. It's part of the reason why Rapid is so strong and why you get finished off by bombs in so many weird ways.
As for this weapon, I've fallen in love with it. Autobombs are fantastic and score too many splats. I kind of expect to see them nerfed a little bit in some way, whether they shrink the detection field or make them detonate faster during the chase. Stingray is actually quite a good special, I got more assists and splats from it then I'd ever want to admit and it does a good job of chip damage and surprise splats. The kit synergises with the Machine in ways I never expected. Combining that with favourable maps for the weapon and the removal of Damage and Defence and you got quite the formidable weapon. It no longer has to be super stealthy as it gets splats quite reliably and definitely has an improved ink coverage which helps manoeuvrability. I got quite a few triple splats and never felt hopelessly outclassed with it against other weapons. It handles Inkjet users fairly well and destroys Ink Armor pretty quickly too.
I don't want or need the Neo, it may come with an arguably better special, but I don't want to give up the great Autobomb in exchange for a sub weapon that I feel is fairly useless for the Machine (not to mention that Autobombs partially do the same job in how they function). I've been able to make the Stingray work quite well, and as a special that isn't key to big pushes I can sacrifice using it for a Rainmaker push and letting others use their specials. I occassionally used Stingray at bad times, but that is purely my fault and something I'll ensure doesn't happen too much in the future. This weapon made my session tonight really enjoyable, something that's been lost in the current meta that makes a vast majority of matches stale, repetitive and quite frankly boring. Here's to the Sloshing Machine's arrival and long may it reign!