FYI, recording a mono source (like a guitar, bass, or vocal) on a mono bus to a mono or stereo audio track…
- CPU usage is the same (during record and playback).
-The recorded file is the same (both are the same size and both are mono).
- Panning works and sounds the same (pan it or not).
- Some stereo VST effects will not work properly when inserted on a mono audio track.
- You can easily move the recorded audio on a stereo track to a mono track and vice versa if for some reason you find it necessary.
FWIW… I always pan my bass and vocal audio tracks.