I personally would go as small as possible for the street that still makes your target HP. Even a stock HX35 over S475 will make 675 HP. In my opinion, smaller faster spooling turbos are more fun for street driving than larger turbos that run cooler.
For example, my truck with the HE351cw is more fun to drive than my friends truck with very similar mods and 62/71/14. My turbo does not pull as hard on the top end and suffers from higher than normal drive pressure in upper RPM's but it's a screamer around town or out horsing around in the mud.
Sure my truck hits 1750-1820* EGT in the 1/4 mile, how often in a legal street driving situation do you run from 0-95 mph WOT? I like stabbing the throttle in 3rd gear with a responsive turbo that makes power immediately and still has enough airflow to make 500 HP.