If your talking about the 360 XDK I would just leave it where it is. At least that's what I do. I don't see the need to fix what isn't broken.
Im in this boat as well. If you're like us and use it for a retail system (which is not the smartest idea) then updating is the better option. If you're not using it like such, then I suggest not updating it.
I was not aware of this. How would you downgrade an XDK? And are you talking about the side with the retail dash?
XDKs can downgrade with the recoveries. To downgrade an XDK, insert an older recovery disc. (Downgrade little by little, like 21256.18 to 21256.12. Don't attempt something like 21256.18 to 1888.0) When you downgrade with an older recovery, the retail dash gets downgraded as well.