While narrower gauges are somewhat more favourable to tighter curve radii, ultimately the difference is negligible enough that it can be ignored. At the extreme end of the range, curve radii for standard gauge trams can go down into the 10 – 15 m range just the same as metre gauge networks, and for mainline railways curve radii instead are usually limited by vehicle geometry and mostly line speeds (centrifugal forces), which (especially the latter) aren't related to the track gauge.
You're right about switches though – if you keep the rest of the switch geometry (angle, radius) the same (and to some extent you have to if you want to keep existing speeds across switches), the large track gauge alone will make the switch somewhat longer, which at least in complex stations with huge clusters of switches (like e.g. https://www.google.com/maps/@50.1039604,8.6563677,197m/data=...) could potentially cause some headaches.
You're right about switches though – if you keep the rest of the switch geometry (angle, radius) the same (and to some extent you have to if you want to keep existing speeds across switches), the large track gauge alone will make the switch somewhat longer, which at least in complex stations with huge clusters of switches (like e.g. https://www.google.com/maps/@50.1039604,8.6563677,197m/data=...) could potentially cause some headaches.