I recently got my hands on a set of NYXL's from the wonderful Adam Ironside at @D'Addario UK.
I've used Elixir coated strings on all of my basses for just over a year. I tried to switch to brighter strings such as Rotosounds and even other coated strings like DR black beauty's but my soft little finger tips couldn't cope with the abrasion (My attack doesn't help).
When i put the string onto my Psyclops bass, i felt a much softer surface from the nickel layer around the steel string.
The tension was a bit high but i am used to slightly lighter strings and i haven't set the bass up since before summer.
The more chrome-ish look was a nice switch from the more dull appearance of nano-coat elixirs and the bright tone was incomparable to what I've known on coated strings
When installing these strings i noticed very little de-tuning.
There was still the slow shifting of the neck that flattens it over time but the string was beautiful with the near stretch-less tensioning.
Pared with the Fender Hi-mass bridge i have on that bass, the sustain is brilliant.
The main downside i see with these is the price. They are pretty much the same as an Elixir set but don't last as well.
If you're anything above an occasional player and want a wide range of capability from a string, i would recommend that you try these out.
Cheers to Adam for the set and i hope that this thread will give you some insight into my opinion on the strings.