Still pretty much useless answers as for any kind of comparison between the two.
My experience with the X-Statik was that it was more of a "fun" audiophile speaker. The 2 enclosed woofers provide a lot of thumping bass for a speaker of this size. As such, the bass is not as clean and tight as it is on the NX series - but has more bass without a subwoofer. The mids and highs were very clear. Imaging was excellent - in fact the imaging was the best I had heard until the NX-Tremes. The highs were the weak point IMO. Initially they were quite harsh, but they settled in and sounded very good without blowing me away. That's not to say they weren't good, they just are the weak point in these speakers (for me). The mids were vibrant and had excellent tone. Everything in the midrange sounded big, open, and beautiful. The soundstage was big, but a little recessed. Singers often sounded like they were 20 or 30 feet away rather than 10 feet away or standing right in front of me. Overall I would comfortably pit the X-statiks against speakers in the 5-10k range.
The NX-Treme's (and by extension most of the traits should be similar to the Otica's) are a different animal. Whereas the soundstage on the X-statiks is big, the soundstage of the NX-Treme's is huge. Absolutely massive. The sound envelops you. They are infinitely open sounding - never do you feel like anything is coming from a box. The imaging is absolutely pinpoint. Try listening to the track "The Holy Men" by the World Saxophone Quartet. If you can't point to a specific point in space where each of the 4 saxophones are coming from, then you don't have the imaging that the NX speakers produce. The bass is extremely fast and tight. For me, it doesn't hit as hard as the x-statiks but its faster and cleaner. I have subs for the stuff below 50 or 60 Hz anyway. The highs are gorgeous. No harshness right from new for me and only got sweeter as they opened up. The mids go from beautiful on the x-statik's to gorgeous. Lush, vibrant - tons of layering. Also, these speakers are the only speakers I've ever heard which can produce "compression". Listen to the song "slip" by Deadmau5. There is a note in this song that repeats. If you don't feel like you're physically being punched in the face then your speakers don't produce compression. The layering is incredible. Electronic music is something I don't normally listen to - and I only enjoy it on these speakers. It doesn't captivate me on any other system I've heard. For me, these speakers elevate every single recording. They show you the flaws, but at the same time they make it better.
I don't know what else to say - the X-statiks are great for what they are but the NX speakers immediately put you in contention with systems costing hundreds of thousands with just the speakers and maybe 10k worth of front end gear in a decent room.