Forgive me if this has already been posted for haven't read everything
in this thread.

It seems that most people here are trying to place a hard definition,
using MTF, on whether a refractor or reflector is superior.
Ubnfortunately, throughout the years, the value of MTF measurement has
been greatly overstated. It certainly is a wonderful parameter during
design and often during quality control but it has no more validity
than other parameters such as wavefront aberrations.

Having said all this, a useful concept that was suggested in the1970s
was MTFA. This is the area under the MTF curve. There appears to be a
fairly good correlation between perceived image quality (whatever that
is) and this simple parameter. How does this parameter compare with
the other discussions in this thread?