I just noticed this thread and it's really good timing because:
1. I would like to replace my OOIS code by either SDL or SFML;
2. Ogre3D people are considering switching to SDL or SFML too (instead of OIS and custom windowing code), but SDL is maintained by people at Valve so it looks like a safer long-term bet, while SFML is far nicer on composability and simpler code. In the end, an experiment using SDL is going on and I think have been merged. The discussion is there:
http://ogre3d.org/forums/viewtopic.php?f=4&t=79237 3. The STL mail is good feedback too.
Basically, SFML is a very close challenger to SDL when it's used as basic layer for the windowing and input system, and that's a good thing but it's not yet the best long-term choice.
I prefer SFML personally, and I target only desktop in my current game so I'm almost sure I'll use it instead of SDL, but frankly on the long term it seems that SDL is always a best bet (until Valve people or other people related to game dev are starting to contribute).
Now, the important additional feedback that you can get from Ogre:
If the windowing system could be separated from the input system (maybe in an optional way?), it would allow a better composability, for example when you want the graphic rendering system to use a specific windowing system, and a very different input api, all sharing the same window handle from the windowing system.
Also, lack of force feedback info in the input.
