There are two issues he

A) The chromatic correction of a comercial SCT has spherochromatism
left over, this washes out subtle color detail
B) the surfaces of comercial SCTs are not as smooth as the surfaces in
Maksutovs (all spherical) due to the corrector plate and the secondary
mirror not being spherical.

However, the effects are very small, and unless you are using scopes
side by side and measurebating, its small enough not to matter.