Perhaps we can inject a little factual information into the medium-width-beyond-Springwood debate here. A recent TOC waiver for transporting (wider than narrow outline) NDSF side dump wagons between Springwood and Lithgow contained the following restrictions
Past all platforms 20 km/h
On UP and Down Main from 109.430 km to 109.599 km (curve approaching Katoomba) 20 km/h
On UP Main from 123.5 km to 123 km (in the cutting between Blackheath and Mt Victoria) 20 km/h
On UP and Down Main between 126.720 km and 126.980 km (Western end of Mt Victoria platforms to yard) 20 km/h
Through the Zig Zag tunnels 30 km/h
Now I don't know how the NDSF wagons compare size-wise with the medium width outline, but I can't find anything to suggest they have any restrictions through platforms in the medium width area. So this suggests there is still work to do on platform clearances west of Springwood.
The Katoomba approach restriction (109.430-109.599) could be the dwarf signal clearance issue mentioned above.
Definatly no problems with them inside the Metrop area and they can even be tipped while in a station alongside a platform.