The idea that lie behind using an instance is to spare as much as possible our dev free time so they use it to fixe and to load page, compare, reproduce, etc... Using a ticket with an instance they got all regrouped in one place.
They can also import a snapshot of the db to work on your sample.
Finally (and even if not in your case) test on a new Tiki instance often revealed a different behaviour than on a Tiki you are working on.
I suggest you to use an instance also.