Hi, I've been DK frost tanking for a while now, just doing heroics and such, and I have finally found a guild to raid with. Thing is, they're saying I'm undergeared to main tank the content they're doing (Naxx/OS 10(They've just formed)). Are they right? Do I need to gear up a bit more or do I need to alter my spec a bit, or possibly both?
Whoever is telling you that you are not geared to tank OS 10 or 25; or Nax 10 or 25 has absolutely no clue what they're talking about, or,they don't trust their healers. You are more then geared to main tank that content. That said, if you don't know the fights (more so Nax then OS), then that's a more legitimate reason.
In sum, your gear is fine.
On a side note, I'd suggest trading out your Glyph of Disease for Glyph of Unbreakable Armor.
I am not going to pretend to be an expert on DK's, but I totally agree. You are definatly geared for OS / Naxx 10 or 25. There is definatly room for improvment, but you look totally fine. There might be other reasons they would be saying no to you, 'cause it 'aint a gear thing.
You should be fine for os,naxx 10 and naxx 25. I woulkd only be concerned in patchwerk though. Unless there is annother tank with more HP then you beeing nr.2 in threat, otherwise you are perfectly fit to tank it.