Kindly disagree. My opinion is that you won't find remarkable differences in pot behaviour with 1M vs 2M inputs... If any.It's not so much about frequency degration but about how differently especially the volume pot acts when presented different impedances. This is where there's really clear differences.
You'll find clear frequency degradation in 100k inputs, which won't occur with 1M inputs, or higher. But pot behaviour is not a problem AFAIK.