Penetration vs -cold resistance

So I am trying to balance something here, I have one free slot to chose either enhance on the snipers mark I already have, or put a ilevel 15 frost bite.

My question is simple, if I go with frost bite as a second curse in my build I need to remove ice heart annoing which is 6% cold pen and annoint +1 to curses.

The question is, is a level 15 frost bite better than a 30 cold damage + 6% cold pen from ice heart ?

Use pob to answer that question.