This issue interests me from more than a mere philosophical perspective. THe quality of preservation is extremely variable at the EM level, and you have to section through lots of material, even after processing using automated apparatus, in order to get cells with minimal ice damage. I guess what we need to know is what are the consistent artefacts induced by chemical or other non-freezing fixation, and can we take these into account and still get useful information from this work. HPF - there are some consistent, worrying artefacts.
Unsupported membranes seem to be a problem.
So I guess you have to argue your case each time. It is important because the fine ultrastructure of some cell structures is still contentious, and we need to know if differences reported by different groups are due to various fixation artefacts or to differences in species used, tissue type, etc. I would also be interested to hear of others' experiences and opinions. As with every technique, it has its limitations. If you cut it down to pieces of that small size, you have to face the problem that this induces alterations in ultrastructure that will increase severely with time until fixation.