It’s fairly reliable nowadays - pretty sure we switched to OpenAL Soft long ago, which solved a lot of our problems. Which manual page did you see that on?
You should be pretty safe using formats like .wav, .ogg and .flac. I would suggest .ogg or .wav since Panda3D can load those without relying on ffmpeg in 1.9.0. Avoid .mp3 like the plague if you don’t want to pay up lots of royalties.