I am having some debate between arena gear for my 5v5 team. I have complete access to all T6 loot for pvp usage. So my question is, 2pc fel/2pc dread, 4pc dread, OR 2pc dread/2pc T6. I was debating this with a friend because I am SL/SL for arenas and the HP return from 2pc T6 is really nice, but is it worth the hp/resilience sacrafice? Also if it is then what 2 pcs of T6 would be used in substitute?

Thanks

Not knowing your exact situation, ie how many arena points and/or honor you have at your disposal, i would say take t6 shoulders and chest, and rest non crit s1/s3 pieces. This way you get both 2 piece bonuses and save some points on the chest and don't have to reach 2000 rating for the shoulders right away. If you find the hp return from the 2p t6 not helping enough, you can always go pickup the chest and shoulders later anyway.
All this is assuming you gem and enchant the two t6 pieces for PvP of course.