Richard
Welcome to IceInSpace.
How is the light pollution up in Tennant Creek these days?
I think the scopes & guider you mentioned are fine. The
QHY5 is another popular model guider.
In terms of issues, the main ones will be the amount of equipment you will need and the stability of your mount.
You might consider using your existing scope as a guide scope (!!) and the new scope for imaging.
Have a look at the scopes over at
andrews to give you an idea what is around. Also keep an eye on the second hand ones here too.
keep asking questions...
James