Yes you can just stay were you are, but it's highly recommended to update IOSes, cIOSes, channels, homebrew apps and after backup your nand (because of changes) if it's not already done.
It's not necessary to follow all the 4.2 softmod guide another time if you're Wii is already softmod. Just check for updates, know what you're doing (be safe)... and it will be fine.
Hope that I've helped you,
- TiWill -
EDIT: Can you show me your SysCheck report? It would be a good idea :
EDIT 2: Dop-Mii is not a tool for updating cIOSes. Only Nintendo's official IOSes and Channels. So don't use it for that or you will install a stubbed version of cIOSes!!!
So, with Dop-Mii :
- Official IOSes and channels : Yes
- cIOSes : Like you said, " a big no-no! "
Instead, you can find newer cIOS wads on the wiihacks softmods guide that can be install with Wad Manager 1.7