Perhaps I wasn't clear in my post... can be omitted != must be omitted. BR and BG isn't particularly useful for A500 if you don't have side expansion attached, and most internal ide/cf solutions (which are way more popular) doesn't need those anyway. I find eMMC controller of AM335x superior to any dma solution you can hook up to side of A500
And I do not suggest to remove BG and BR from the design, only that those are not absolutely essential signals which are required for amiga to work.