If I have an area with bus-only road top stops and I build a new subway through the area, would it be more beneficial to convert the bus stops to bus + subway stops or to add subway-only stops adjacent or nearby? I've found that putting separate bus and subway stops allows for more capacity but does it also slightly increase commute time?
Convert the bus stops to bus/subway stops. Less walking for the sims and less congestion since the capacity increases.
I agree with k808j, but I'd also like to point out that it's been found that the capacity of mass transit stops is essentially meaningless, as discussed in the thread RTMT Station Capacities (http://sc4devotion.com/forums/index.php?topic=9552.0). So the congestion isn't affected either way. The main reason to use a single stop is for aesthetics; it's less cluttered, and you can't put two stops right next to each other anyway.