Which telescope to choose and some general questions
Macs also need to be collimated, but much more rarely than Newtonians.
 They hold their alignment better (for more time).

For astrophotography you also have to think about the field of view each scope will give with the camera a that you will use and the fact that their mounts are not equatorial (less important if you are into planetary photography).

I see that the Mac has a Vixen dovetail, which means you can later use it on other compatible head mounts or put some other scope with the same dovetail type to the SLT mount.

It might be cheaper to wait more time and buy from the beginning the "right" equipment for your task, than buy something cheaper and then replace its parts.

Cheers!