I am of the opinion of get her done. long as you are running good filtration removing the substrate and replacing should not be an issue, with good filtration and bio media it should not send you into a mini cycle. I do not count on my tanks substrate or decor to do my bio filtration, that's all canisters and HoB to some extent.
SKJ, I run a duel bottom drilled reverse UG system on my 180. 5" of crushed gravel pushing 1300 gph, I also run 2 AC110, I have had no water issues and my white crushed has looked great for past 2 years. good vacuuming and 90% water changing every Saturday helps. stuff never settles in the gravel but is pushed to the side for easy vacuuming. intakes have large sponges on them, cleaned once a week.