I have stayed in both and I would only stay at the residences now if I am with family. You get daily house keeping and turn down, an empty fridge but can request it to be stocked, full access to the hotel facilities including lounge, and our 11 months old now is welcomed, and a bath where most the hotel room doesn't have unless you are in a suite. I must say it is not the nicest or in the best spots, and the furnishing is on the lower end of the scale (same as the hotel). However, I must say the service in HSP is as good as HSW and Brisbane, and they are more relaxed about taking your sparkling water with you out of the lounge.
You basically get a larger room with very little down side. To me it is the inconvenience of carrying the two keys, one for room and one for lounge, and that you have to get down to the public area before you can get to the lounge.
If you know your way there are two exceptional but cheap Japanese Restaurants in the area, and Salt was very good the first time, but our last visit wasn't the best (dinner). HSP has taken over from the Sheraton Mirage and the Versace as our preferred place to stay on the GC.
Did you get lounge accesss because of status or because of your residence Booking?
what sort of breakfast is in there? Hot or cold?