X-rings in PCP's?

[FuzzyGrub]

Would X-rings work in PCP's?  Would they provide any additional sealing capabilities, or just cost more?  Just wondering.

[Motorhead]

Use them in my Poppet stem mods because of the there low drag in a NON static application.
In a static application why

[nervoustrigger]

I'm curious what others have to say but I don't see the benefit.  The cross sectional shape provides two sealing surfaces vs. one for a traditional O-ring.  But it's not like both surfaces share the sealing duties equally because a seal is only formed where there is a pressure differential.  So the first of the two surfaces to seal will be carrying all the load, just as it is when using two conventional O-rings back to back.  Presumably there's some benefit if installing them where there is a risk of nicking the seal on installation which means you're banking on a luck element.  Lucky that one gets nicked but the other somehow doesn't.  It has been my experience that if there is a burr, it will cut two O-rings just as quickly as one.

Scott, regarding their use to seal a poppet stem to a valve, wouldn't a traditional O-ring be just as apt to provide low friction if its ID is a close match to the stem's OD?  I know some of these applications capture the O-ring with a washer and put a squeeze on it which presses it against the stem, but that's a design issue to my way of thinking, not an inherent advantage for one O-ring cross section over another.

[FuzzyGrub]

I was wondering as the x-ring ages and takes a set on the 1st sealing edge, that the 2nd sealing surface would hold. 

PS: I did see Scott's valve stem mod, but was wondering about static high pressure sealing. 

Again, just wondering, and had not seen it discussed before.