I never use Irish moss (or Whirlfloc) in Lagers... not that there's anything wrong with it. I just think it's unnecessary. My lagers come out VERY clear. (I don't filter either.) The only less-than-clear lagers I've had were due to mash temps (rests) inappropriate for the malt. But I've fixed all that now. Lagering for the appropriate time really clears up a beer as long as mash temps were appropriate for the malt. (I do use Whirlfloc for ales.)
However, I will put in a disclaimer that I've only ever made lagers with pilsner as a base malt. So, I don't know how 2-row, etc. would do with clarity, but I don't think it would be much different.