I disagree.
You can use:
A. Marc Card/Ghostring
B. Detale Card/Ghostring
or my personal favorite
C. Evil Druid/Tao Gunka
By chosing to use a hat other than Fhelm you are sacrificing either freeze immunity or your tao bonus in exchange for more damage, (vote hats like kobold, mage hat), more reductions (deviling hat, santa poring hat), strip helms (amistr, leaf cat, drooping lif, etc) or even another useful item (phreeoni hat for improve concentration, valkyrie randgris helm for dispel, helm of hermes for perfect dodge, medusa hat for stone curse). So although you lose your immunity to freeze you are still receiving another useful bonus. Plus 90% reductions (almost all classes) would have only one drawback in that they cannot deal strong damage or 95% reductions (stalkers) who would have no reason not to wear full reductions 24/7, although most do anyway.