(Otherwise stock Elantra Sport 2017)
Personally, so far I love the V2, it literally put a smile on my face multiple times driving it yesterday. The vibration is definitely a bit ridiculous though. Speaking to the noise and vibration alone, I was surprised how much louder the engine cabin noise got too, and the tone changed as well. I think it sounds way cooler, and the vibrations make it feel like it's actually a sports car with an engine, rather than a quick car with a floppy surgey turbine. The sound of the engine is deeper and sounds less like a struggling four cylinder at higher RPMs, and you can hear the transmission sound now too, which I personally like. I don't think it's as loud as a BRZ or a 2018 V8 Challenger on the inside (other than that ugly 1000 RPM zone), but it vibrates more. At cruising speeds I actually feel less vibration than before though, or at least the same amount, and the sound levels are basically stock. I had to take my sunglasses out of the top compartment and move them to the center storage area to avoid them rattling around, but I didn't actually feel like the car actually enough for that to matter. I've always had a rough-ish idle since the car was new, and when I'm at a stop light with the turn signal on, the load on the alternator creates a matching oscillation that vibrates the car like a subwoofer beat. I think that's the only part that bugs me, but as far as I'm concerned the rest is absolutely worth it. I think the vibration is actually super cool, and I'm not one to like that sort of thing normally. Like everyone says, the roughest part is around 1000 rpm, that's probably the only part you would have to explain to a passenger as "Don't worry, the car is fine, that's just because of a mod I installed". The rest of the vibration kind of matches the stiffness of the suspension in a way. I feel like now I won't have to feel the need to apologize to passengers about the rough ride, since the engine matches it now too, making it obvious that it's a performance car and not just an Elantra. The job is super easy, I recommend a lift (obviously), or a jack if you're comfortable getting it up. Personally I just used Rhino ramps, and it took about an hour including time spent digging through my pile of sockets for the right sizes. With the rhino ramps it was a bit tight, I only got about one click on my torque wrench at a time, but you should be tightening with a normal ratchet before you torque it down anyway. I think the hardest part with the ramps was getting the transverse bolt lose. I used a breaker bar and kept removing my socket and rotating it 90 degrees so I could get a decent angle on it, then kicked it loose.
On to the "performance gains":
I haven't experienced wheel hop again, shifting is so much smoother, and the surgeyness of the engine is no longer amplified by the engine flopping around in the engine bay. I wouldn't be surprised if 0-60 time is actually improved. I went around a small, really windy and hilly neighborhood I tend to go fast in due to the 30mph speed limit being actually too high, following my friend in his GTI taking turns hard and pulling through the corners. I didn't expect this, but it felt like the power much more reliably got down to the wheels, almost as if I had added some sort of software package to do the whole fake LSD braking thing. Not quite there, but enough of an improvement that I was genuinely surprised and delighted. I had traction control off, tires spin easier, but the deathly jerking wheel hop from the spinning is gone, so it's very controllable now. Just ease off the throttle and the spinning smoothly stops, in the same way a RWD car can be controlled through a drift using the throttle. Only differences is you're not drifting. I've never gone to a track before, i.e. no professional training, I don't even know what an apex is, but I definitely feel like there's actually less understeer in this controlled wheel spinning. It might not actually be less, but it is definitely easier to control.
My thoughts on the N-line version (haven't owned or experienced):
The job was super easy, so either one is worth a shot. If you don't want the vibrations and you'd like to keep it more refined while getting rid of the engine slop, try the N-line and see if it's good enough. Based on what people are saying in the forums, you will be pleased. Personally I wonder a little bit if the N-lines feel different after break in, since I felt like stock was pretty stiff when I first got the car, and it got sloppy after a few years. But if the N-line ends up not being enough, it's so easy to swap and not super expensive to throw in the SXTH later down the line.
That being said, the SXTH makes me really want a more grippy clutch. The shifts are smoother now, and the power gets to the wheels faster, but I don't get the hard pull on a drop shift from redline like I would in a GTI or a BRZ. The clutch just can't grip fast enough, and with everything else in the car being stiff and sporty, it feels out of place being so fluffy to engage. I had barely noticed that I wanted a grippier clutch before the mount, but afterwards it's a clear weak link in the chain. On the other hand, redline shifts are more comfortable now, and it's also possible the lack of hard pull actually comes from the turbo lag between gear shifts rather than the clutch.
Install was super easy, took an hour with ramps including digging around for tools. Ramps make using a torque wrench and a breaker bar tough, but still doable.
If you like the way muscle cars and Subarus vibrate (but don't expect a V8 feel obviously), and don't mind some extra harshness at 1000 RPM, and you like the idea of your engine sounding cool instead of sad when you push it, SXTH all the way.
If you only want to get rid of wheel hop and engine slop, I'd give the N-line version a go, since it's not a huge loss if you decide to swap it out again. It's probably enough of a difference, especially if you're otherwise stock. I kind of wish I had looked into N-line before buying, but I'm super happy with the SXTH