Salvete!
Owen asked if anyone uses the "MARC view" in the OPAC.
As a cataloger, I use this on a semi-frequent basis when I get sick of all the tabs to view a MARC record in the staff client. On a related note (and a reason why to keep this public), I often view other library's MARC records to compare something or other. You're right, though: I don't think many typical users would ever view the MARC record.
I should hope that it stays as well. It's a feature that's pretty standard in an ILS, and is quite handy for cataloguing. However, I'm not at all opposed to sticking it in small inconspicuous font in a lower corner of the page to not clutter up the display for Patrons. If we decide together, then the Koha community of cataloguers would know where to look and click. I do appreciate the spirit of decluttering things; I'd love to see a first page similar to 2.0 days with a text box and not much else. One click down could have all the cool catalogue art. Cheers, Brooke