As pointed out in Bug 7491, the item-level_itypes syspref has two functions. In the words of the documentation: * This preference determines whether the item type Koha uses for issuing rules will be an attribute of the bibliographic record or the item record. * It also determines if the item type icon appears on the OPAC search results. If you have the preference set to 'biblio record' then Koha displays the item type icon on the search results to the left of the result info. It seems to me that it would be a good idea to have two different sysprefs for this - libraries might want to alter the display in the OPAC independently from how they handle their issuing rules.
I suspect that this description is too generic to have a patch. A discussion about this has also been opened on koha-devel, by joubu, a few months ago, but we couldn't reach a consensus and/or a validated patch. Closing this one