There are some...unclarities in your post.

I take it you mean being able to play wiiware from an emulated nand (if you install the wiiware to your wii itself, it's not that hard to get it running). Rev21 fixed the broken support of rev20, but it still requires you to use the correct base IOS*.

Second: cIOS'es are installed to slots. Though 249 is the most popular one, it is by no means the only one (though triiforce and mighty channels currently have no easy way to use another one). If you play your games through an USB loader, you can already select which cIOS (slot) to use to run a certain game. You may want to install the newest cIOS'es to numbers like 246, 247 and 248, and keep your 249 almost strictly for wiiware loading purposes (despite quite some successes with mighty channels, I still have rev17 in that slot).

Also: keep in mind that nand emulation doesn't have full compatability (unless you use sneek). Make sure you test a game that's known to work first, or it'll be hard to tell just where things went wrong.

Also: triiforce isn't updated much nowadays. Marc Max is making good efforts with mighty channels, but even he can't do much to improve what the cIOS isn't capable of doing. uloader (with its ugly interface) or sneek (which is still not easy to set up) remain valid alternatives.





*I've been on vacation...I think this was base IOS 36, but you may want to check the mighty channels thread to find out for sure.