> What we've learned is there is little ice on comet
> surfaces and certainly nary a trace on 67P, but
> apparently the coma is water heavy.
How can you make such a claim? You obviously missed the ESA conference last June, where the presence of water on P67 was discussed. Ice is present as sub-surface material, as volatiles and even as bright patches showing through the dark surface material.
Here's the link to the conference. You might like to listen to it:
Here's a direct link to the ESA discussion of the ice that is actually exposed on the comet's surface.
We discussed this in detail a few months ago, on this long thread