Never had the opportunity to ski the NFX but I've owned two pair of AR7's.
The two pairs of AR7's I've owned have been excellent skis. They're durable, they should make it through at least one season of heavy park abuse. The bases are great, hold wax well, fast, and durable. Flex is on point as well, the noses are a medium flex which gives the ski a bit of a playful feel when doing nose butters, the tail and underfoot of the ski is noticeably stiffer than the nose which makes the ski feel very stable.
I've never had any problems such as washing out when hitting the largest features on my AR7's, the bottom line is they're a reliable, powerful, and awesome park ski.
Here's a great review on the NFX that you should read: http://www.newschoolers.com/membernewsread/No-ing-Excuses-Salomon#wROvg0okBECOl8ha.97
The best way to decide though is to demo the skis. Try find somewhere you can demo them and really get a feel for the skis.
I like to ski with loose underpants or boxers on so my balls can swish around and chill.