Not really sure what you are trying to hit. Your first targets anyway are going to be squishes most of which cap their defense out at 20% thanks to DR. Most of the scrappers you will run into will Be Regen. Tanks will be Inv and Fire, with the occasional shielder around but at that point it will likely be one of the last to go down anyway.
Really the only thing I think that is hard to hit Blue Side is the occassional SR scrapper you run into, and they are definitely a rarity from what I've seen (On Freedom zones at least)
I'd focus more on getting more KB protection more +damage, maybe a little more +HP and more +recharge.
Give your budget or your apparent one with the expensive PvP IO proc and some purples as well as the LoTG's and health procs I'd maybe look into going stamina less and fitting in leadership
I have never made a stalker before for pvp so here is my first try at one.
This stalker is going to be for zone pvp only and i hope the accuracy is going to be high enough to hit things.
If you could post any thoughts that would be great as i am trying to get better at making pvp builds.