If you are prepared to go with jap wheels, in my experience, 4 stud is generally not a problem.
I was in the same boat. Keep 4 stud or convert to 5.
I am not sure about brake upgrades, but every wheel i was looking at came in a 4 and 5 stud version and a normal and deep rim version for each.
Good question, i would like other peoples opinions.
Is there are decent 4 stud brake upgrade?