This issue needs attn. My personal experience its either wizards or rogues or the combination of both. Last two games had both in the comp and it was causing 4 of the people in my group to crash at lease 3-5 times in a game.
Most healing spells are % based on your total hp so more con/hp you have the more you get healed for so Con is definately a great stat to pump for pve and pvp.
Threatening rush is an awesome way to generate aggro, since it doesnt have a cool down you can use it to leapfrog from add to add and the AOE mark will generate threat over time. Also if you spec into threat talents its builds a good amount of threat. single target marking mobs is not what they meant for the guardian to do.
Also once more experienced pvpers get 60 with similar gear im guessing your crit/recovery/power items arnt gonna be viable since you will be so squishy.
Crushing pin > Improved vigor for the pvp build since you are focusing on burst and you will be rolling around with 3~ prone abilities you would be better off. Also I think Crushing pin gives your team mates the 10% bonus as well. The improved vigor is only 10% as well only if your hp is low so thats kinda sketch, also i…
Having companions in an instance is just imbalanced imo. As the OP notes the problems with tank pets taking a player's role away in a group as well as having say 4-5 healer pets keeping up with the dungeons seems OP. I would vote for removing companions all together.