I meant to give some practical examples last night.
Here is 1hr of the Rosette in summary, 8" Newt, 450D, middle of summer, from surburban skies. If you look at the full picture the nebula detail is only just coming up out of significant sensor noise.
https://photos.app.goo.gl/7nhXpZ4MAWCXTH1h6
2nd pic is 1hr of Ha data from QHY9.
https://photos.app.goo.gl/Em4GcmTR8gR57Fq98
CMOS cameras with their high QE will likely show a greater improvement again.