Interesting looking filter DC. Nothing wrong with using a filter to do the job. What it generally comes down to me with filters is first, can I do it better with the filter by hand or with the filter, and second, which is more cost effective. Does it cost more to purchase the filter, or continue to do it by hand. Of course, that depends on how many photos I am going to do, and how easy/difficult the task is, and how easy/difficult the filter is to use.
Either way, it's always a good idea to know how to do what the filter does, (when possible), in case you need it when you don't have access to the filter.