It's more complex than that. There's no right answer and therefore every answer is wrong :(
For more critical observers, you're right: raw input is preferred. However, most users (casuals) expect similar settings as their OS. It's probably best left up to the user to decide, but to default things to the OS legacy settings. A more advanced player will know to tune the settings while the less advanced just want to launch and go.
No. He's right. No fps gamer expects the game camera speed to "match" mouse movement speed. Raw input-> mouse DPI * in game sense = effective dpi.
Everyone has their own preferred edpi. This was you can change mouse or computer or in different games, you always get consistent movement.
Everyone plays fps games. This includes people who wouldn't consider themselves "fps gamers". Users who care about mouse input will go into the settings to target the 'correct' settings for them.
For everyone else, there's the OS values.
We're not having the same argument, but I didn't clarify in my initial post properly: It's best to launch your app for the first time with the default OS settings. Let the "power users (fps gamers)" tune settings that enable raw input.
that's just going to result in the non-power-users having a crap experience and not knowing why. Mouse acceleration is not a good match for FPS at any skill level.
I'm not aware of any studies on this, Nvidia did do a study on the effect of sensitivity on aiming [0] but I'm afraid it didn't cover acceleration. Imo it very well could be given how many top aimers and pro players have successfully used configurable mouse acceleration solutions like RawAccel, InterAccel, Povohat's and Quake built-in acceleration. I feel like aiming with acceleration has a steeper learning curve though especially with steeper acceleration curves without an offset, so perhaps I still wouldn't slap default windows acceleration at newer players.
Surely even in a shooter game you spend some amount of time in menus where you do have a cursor, right? Is this why I sometimes get completely 'wrong' cursor movement in games?
In those type of games, you aren’t controlling a cursor, so there’s no “expected behavior”.