Keep in mind I am going back to 1987 in my mental database, it was in a US Ironbird, all mahogany with a Kahler and BC Rich pre-amp. It was great fun to flip that switch when doing old Stooges tunes.
You know that pickup originally was created as kind of a gag. Someone at Dimarzio got cute and was trying to be funny by buliding a big massive ceramic mag pup and it worked...the X2N was born!
That's similar to how the Invader was created. It started out being the "Darth Vader" and was made because someone wanted to see how much output they could get out of a passive pickup.
I'd say it's pretty balanced, and does have some compression. But tone curve questions are the wrong attitude. You don't ask "What kind of fuel economy does that Ferrari get?" You ask how fast it goes.
X2N Tone curve? Whatever. But it is Mother ^*%^%#% LOUD!
It will alter the tone of your guitar- by boosting the amplitude of all frquencies to the ceiling. Thus, balanced (flat) and compressed. But mainly LOUD. A really fun kind of loud...