Critique my HC Build

http://www.pathofexile.com/passive-skill-tree/AAAAAgUABLMFWwx9EGkQfxEtEdsUTRdUGYUabCKBJKon7SlPLJwtHzCXNuk5ikSrRtdN2E99UWBVrlZKWfNdxmBtZp5tGXB9d2J8g31TgFaBb4KbgziLjIx2jjyOvo-mkFWSOJUEnYCdrp48nqGiAKcIqZWsqq-btoa4k8AaxPbGns363fPhc-Nq5CLk8e0g8B_z3frS

i feel it has the most efficent mix of defense and offense

you spend 3 points to get 21% fire res, and 6% to all other resis
and another 2 points for +6 again

instead of going to diamond skin for just 4 points.

why?

i get 6% to all res from each and 15% to fire and lightning for 4 points spent. i ignore cold because i get it from frost walker. therefore for 4 points i gain a total of 27% fire and ligtning res and 24% cold. which is greater than 15% from diamond skin....done got schooled!