Nope. No recent ban waves, netiher any problems to be in a higher firmware version.
If Nintendo knows that you have CFW, it doesn't matter regardless the firmware version, they probably know it already, even for you, me, and everyone in GBATemp... Nintendo knows everything.
The thing is... Ninty doesn't care a lot anymore. They killed freeShop, and for a lot of people, that means no more free games (because they don't have a laptop or a good cellphone to download the .CIA files, or because they don't know how to) and that's what Nintendo wanted the most: no more free games, the homebrew thing and CFW doesn't matter so much to them, and the proof is that unless someone cheats or plays a game before release, nobody has been banned in the last 3 months.
Play without fear, and even if you don't use your 3DS or connect to the Internet, if Nintendo wants, they'll ban us, even the ones that don't use their console… and there're some methods to unban a 3DS, so play with the security that nothing is goin' to happen, and it doesn't matter if you're playing a legit cartridge or an eShop bought game, or even a game you installed through FBI or the freeShop, it's safe.
Also... update to 11.8.0, it doesn't brake anything, and it is totally safe.