Hi Method, I can imagine that it would be a hard decision, to trade your Big Hats for the new ForgeWorld figs.
I am still on the fence on unloading my original bighats, (as they were my first GT army) but my new stuff and the old don’t match…grrr
I too think it is a BIG grrrr, that the New and Old stuff do not match. I personally am a fan of the old Big Hats, but if you want to move forward and have an army with a rulebook (or at list an army list via the Tamurkhan book), then you need to get the new figures.
Good luck on your pursuit and may you have many good trades.