John, my experience with wide angle lenses on the 4x5" format, is that once you start using rise, fall and/or shift, the use of a graduated centre filter certainly makes life a lot easier. Without using any movements you will be working in the sweet spot of the lens, so to speak, but there will be fall-off. How noticeable and how much it bothers you, are variables that only you can decide.
Yesterday and today I have been doing tests with my Fujinon SWD 65mm f/5.6 lens on my 4x5" folding camera. The tests were specifically to ensure that Ilford's reciprocity chart factors work. Whereby one uses a set factor for each Ilford film rather than reading from a pre-printed chart. I figured it would be accurate, and it was, but I needed to test to ensure it does work as I only have at best two opportunities for an evening/night shot of a subject.
The other part of the test was to ensure the evenness of my graduated centre filter under low mixed lighting, LED and Tungsten, in combination with the lens, film, developer and reciprocity correcting method.