Thank you for adding the option for the original sounds in MCC's Halo CE, I really appreciate it.
I noticed a few anniversary sounds still left in classic mode for CE though. The plasma grenade in CE campaign still has the anniversary sound for right before it blows up, but the explosion itself is classic. (But in multiplayer the entire plasma nade sound is classic, so that's good.)
The sound for picking up ammo on all guns in CE in both campaign and multiplayer are actually switched. So when classic audio is on, it plays the anniversary sound for picking up ammo, and vice versa.
The sound the pelican makes while dropping you off in the opening cutscene for Assault on The Control Room is still anniversary in classic audio mode.
The flashlight on/off sound in CE campaign is still anniversary in classic audio mode.
And something other than sounds, the camera turning in vehicles (for both driving and the turret) is very slow in CE for both campaign and multiplayer. It's a lot faster in the original. The slowness in MCC's makes driving and using the turret really hard, especially the warthog and banshee. And the warthog turret camera locks up when getting shot at, it can barely turn and makes it impossible to use the turret.