The question is : is it good or not to have a way to find information anywhere in a record, really anywhere, whatever the field or subfield? I would favor: anywhere=all specific indexes. "Really anywhere" will cost more and will perhaps index fields that you do not even want to index. It should always be possible to exclude a field from indexing.
In fact it raises a second question: even if it is usefull for staff to have a broad (on all specific indexes) or even a broader (on all fields of the record) index, it is a good thing that this index is used in OPAC simple search ? I believe not. Because some data are not made to be searched by an average user, and can even make a precise search on a subject more difficult. I agree.
PS : I'm leaving my position the 6th of december, and I won't work anymore on Koha in 2014:-( . So I will probably "un-assign" soon the bugs I am currently responsible for in Bugzilla. Too bad for Koha, Matthieu. But have success.
Marcel