I downgraded 2DS from 10.3U to 9.2U and CFWed it earlier, thought I'd pop back in to mention I just downgraded my fiancee's 3DS (10.3U)... however...
When using the exact same files, somehow she downgraded to 9.0.0-20U instead of 9.2.0-20U? Very odd. But hey, it worked, she's on CFW now, everything's peachy. Just... weird.
Other than above weird overdowngrade and the issues running sliderhax on 9.2 I had (always download a browserhax ropbin instead of relying on it to download one itself! that fixed that issue) it's been absolutely smooth as butter sailing, the second time only took me I want to say 3 hours total, and that was with a fairly slow microSD card.
Both times I followed the "More Or Less Catch-All Tutorial", though I also poked around to find more detailed steps for sliderhax when it wasn't working for me.