From personal experience I am getting more out of Pyrotech for pvp. I leveled 1-49 as Adv Prototype and then went to Pyro.
If you want to tank and still do good in pvp, well you can just go shield tech, you don't -have- to get every -1% or so damage reduction talent to do well in pve too, it is just min/maxing for operations. I would just get the basic tank gear that drops and use that for pvp if you want to be shield tech, and at 50 just get the sets and you don't have to worry about aim/endurance.