Overall very good idea, on the first read. But later, several thoughts occurred to me.
First, i'll still never play pvp, for the same reason i didn't play by now - my main problem stays - high Ping. I don't wanna be slower reacting then my opponents(i don't think it's fair), so i don't pvp. And other players far from AL servers will also have this disadvantage.
Second, I see this as a big system, so i don't think it is very likely to be implemented. Seems like a lot of work and am not sure sts will get motivated to do it. It's possible ofcourse.
Other things. I doubt sts will choose 'predefined sets of gear', because there will always be some complaints:'Why this particular item is not in that particular set'. Seems better to me, either the player to choose everything he will wear(gear/pets) from everything possible, or there to exist only one predefined set.
And this leads me to my next thought. The only really equal pvp encounter will be only if the players are from the same class and wear the same things. If the players are from different class - at every level cap, from what i read, there are always items that make some class to have some advantage against other classes in pvp; may be not big advantage, but it'll be not equal encounter, between different classes.

Other things. Seems to me, if something new is done in pvp, it takes the players away from the old things(maps). The old stuff die out if the new stuff is better.
And there will be the new guild battlegrounds coming out soon. Which will take a lot of pvp player base, it seems.
So i doubt even more that a new pvp idea will be implemented anytime soon.

Yet, it's a great idea. If implemented and if something is done for players with bad ping(which i'm afraid is either impossible or very hard), i and probably more players might play pvp.
There are often arguments in pvp threads - if possible, don't hate/flame me if you don't agree with me, these are just my thoughts - just say why i'm not right, i'm replying 'ok'. These are thoughts, i may be wrong, tnx for reading