As an LGW based pilot, can I ask what is the advantage of 160 to 4 over 170 to 5?
I think you'd get much better speed conformance using 170. Folk would actually do 170 to 5, instead of 160 to 4 actually being 160 to 5 most of the time.
It's just the time it actually takes to configure after 4 miles doesn't leave a lot of room.
I'm on the A320 but I'm sure the story is similar for the 737.