I think that in your hypothetical situation, the guy who is more experienced will have a better chance of actually killing the other guy, regardless of gear. Winning a fight and landing the PK are very different things. A new player with a set of high quality gear is drastically harder to kill which in turn allows them to learn more. They are not nearly as deadly but the enhanced survivability allows them many options.

Generally if a fight is only lasting two or three rounds its not even hero gear on the table for the victor. At level 15 pretty much every class can amass a dmg roll set high enough from just the item search that is available to everyone to pk people in their bracket. Typically the bigger impact with high end gear is that it allows you to have both dmg roll AND hp not having to choose one or the other like you would typically do with lower level gear.