I use VMix once a year as a playlist-based video playback system for a live event. It's worked well for this overall.
For the most recent event I tried exporting my videos as H264 with PCM (uncompressed) audio in an MP4 container, and was surprised that the video played but the audio did not when loaded into VMix. The same files played fine with audio in other players, such as MPC-HC. I ended up having to fall back on the original files I had, which were ProRes video with the same PCM audio stream in MOV containers, which played fine. It seems that VMix doesn't support PCM audio in MP4 containers?
Audio, even uncompressed, takes up a small portion of the total storage of our show, so I figured I would avoid the additional generation of compression if I could.