Hi Lydia,
If a separate section is needed for identifiers, I do not care.
From the user perspective point of view my question would be what happens when a user tries to add an identifier in the statements section instead of the identifiers section? Besides users are used to add identifier statements to the statements section, it can cause misunderstanding if it is no longer possible to add identifiers to the statements section. I would then recommend (if this is not yet thought of) to allow users to add identifiers to the statement section, and with reloading the page they show up in the right section. (Maybe the other way round as well.)
Also when I currently want to add a statement, I press [ end ] on my keyboard, there I click [ add ]. If I must add the a statement to the right section, this would make it much uncomfortable to have to search somewhere between the statements and the identifiers where the [ add ] is for the statements section. If this would happen, it would make adding statements more annoying. (I would like to recommend to make it less annoying and more easier to add statements.)
An alternative idea to solve this is to be able to add statements at the top of the statements section.
Navigation will be an important issue to have attention for, otherwise splitting it up in identifiers and other statements would make the improvement for users nett less improving but instead worse.
If it is wished for to split the identifiers from the other statements, I would more like it see just all the identifiers on the bottom of the statements section.
If all statements in the source code ( <div class="wikibase-statementgroupview-property"> ) would get an id="..." based on the property number, it is easy to arrange having all identifier properties on the bottom.
At the same time this would be easier for users to put certain properties always on top of the statements section of an item
PS2: Not all identifiers have or will have an URL available.
Romaine