I am thinking about getting the Chromax fans too, but the OP's 120mm poop fans perform much much better than the Chromax series, even the 140mm ones.
Noctua ripped off Scythe/Nidec's silent typhoon series with the NF-A12x25. The new fans have much higher static pressure and airflow at greatly reduced noise levels.
Kinda sucks they're not offered in black. I have to either get poop color or get less performing Chromax. The new Chromax fans won't be available till 2019 supposedly.
Odd, I have not heard anything about the current Chromax fans that I'm using performing any different than the regular lineup. To my knowledge the only change made was the colors. If you have reputable sources that say otherwise, I'd like to review the materials. Mine seem to be doing well.
It isn't the "regular lineup" I'm referring to.
The Chromax is the same exact fan as the regular NF-A14, just with a different color, so all specifications should be nearly identical.
Noctua recently copied Nidec's gentle typhoon series and released a new model of fan with the model number of NF A12x25, that's the one OP listed in his build. They're touting this product as "new generation". As mentioned the design is similar to Nidec's gentle typhoon series. Noctua also reduced blade to frame distance and are using their new "sterrox" material.
You can read about it here: https://noctua.at/en/nf-a12x25-pwm. The product information is also available on their news release page.
It became available last month on Amazon.com. There aren't too many reviews but most users are reporting better airflow and less noise compared to even the 140mm fans.
I'm personally waiting for the 140mm variant of this new fan, apparently those will become available in 2019. Prototypes for the bigger model was shown at Computex this year.