lichborne is far from limited....esp if you dont have a handy shammy for certain fear fests. it can give you a great "oh crap" save.
I agreee Meciless Combat is subpar, not useless but certainly not in the must have grping. personally I take the imp icy talons for the grp buff as my 10m ulduar progression grp does not have a frost spec dps dk or an enh shammy.
I have seen little use for hungering cold. with glyph of HB, I tend to just pull with that, and due to the huge amount of aoe present in most raids the cc effect will go down in less than a second in all but the rarest of cases.
All in all, I like your build...would not use it personally but I see how it can be effective.
I was the lonely voice on my server who simply wanted to know: When Michael Jackson died....did he drop any good loot?