i'm sure that all snipers really like you.I think impenetrable is over rated at times in pvp. The armor traits you use depend on your playstyle and build.
Last week I ran 5 buffer of swift and 2 seducer with wrath of imperium staffs and rings with spell damage necklace, I had no probe in pvp, however I'm a caster that stays out of the front lines, and keeps shields up at all times.
This week in running 5 adroitness, 3 torug pact with the same staffs and rings, again so far no problems. I'm a LA sorc, I'm not supposed to be in the front lines, I have close to 3400 hp with food, and still hit like a truck,
If your in med armor or a tank character, sure you should have as much impenetrable as possible to survive hits as you will take a lot of them. As a caster, damage and max magicka is more important, you need to kill as quickly as possible so other traits could be more beneficial, every build has strong points and Weak points.
Pick traits that fit your style of play. everyone is different. A guildy of mine had a 95 kill streak the other day, and he don't run a single piece of impenetrable and he destoys people. So run what makes sense and maximizes the strengths of your build. If your a caster damage type focus on maximizing damage and killing fast, tanky? Lots of hp and impenetrable, etc.
Armor traits rarely make that much of a diff, not getting hit as much as your opponent often does though.