Actually, CN helps a lot when it comes to XCross. Opposite neutral also (I'll use ON for it).
The XCross is basically a 2x2x2 bloc + a cross overlaping. The 2x2x2 isn't a big constraint on the cross, but the cross is a big deal to build the 2x2x2 bloc (mostly, you need to do an F2L case). Being color neutral or opposite neutral allow you to explore the 8 2x2x2 bloc you can begin with. Actually, you'll look at them searching for an easy pattern.
By insterting few moves in the 2x2x2 bloc building or at the end makes you an XCross.
Remeber : being CN makes you win 1 mvt on average, and ON 0.5 . The big deal isn't here. The big deal is XCross. And ON and CN helps A LOT for XCross. However, if the gain is certain from non neutral to ON, it's not very clear what it is from ON to CN. These guys turn the cube crazy fast, and be sure that if they can achieve such great time, it's not just a matter of CN.
In a short way : go for ON, without any hesitation ! Go for CN if you really want to, but the gain over ON isn't certain. Think XCross.