I've heard that a few folks are using video camera/reducer combinations with these "imaging" style Newtonians. At f4 they are already "fast", but some might like to push that speed a bit.
On paper it should very likely work for most popular combinations ... both scopes either come with or are suggested to use with a 2" extension tube to get most eyepieces to focus (the focal point is quite a bit above the existing focuser). These scopes are designed for imaging setups with cameras like a DSLR which requires more than 55mm of outward spacing above the focuser body. The focusers on these scopes usually have about 35mm of travel and the suggested extension tube for the AT model is an additional 35mm. So there is likely at least 60mm of inward travel available from the original stock focal point.
The Mallincam Micro like most similar cameras requires only an additional 12.5mm of outward spacing ... and then as Glenn mentioned you have to take into account the additional inward travel required because of the focal reducer.
Some examples ...
Antares .5x 1.25" model on a 1.25" nosepiece (actual spacing of about 37.5mm with a video camera) - additional inward travel required is 24mm (will provide about f2.4)
Antares .5x 2" model (actual spacing of 79mm) - inward travel required is 79mm (so not likely to work). If the spacing was reduced to 65mm you likely will be able to run at f2.4. Same speed as the 1.25" model but with less vignetting (edge darkening).