This Field-of-View-calculator could factor into the decision, too.
https://astronomy.tools/calculators/field_of_view/
F5 newt from as small as 130/150mm upwards is great for DSO. The EQ-mount has to be stable enough to support the weight. With newts you get more mm per kg than with refractors.
Tube and focusser need to be able to handle the weight of you camera, as well, so I'd rather not buy a cheap 80mm refractor if you plan to dangle a heavy Canon from its end.