160 to 4 doesn't work on on our type because the F5/F10 speed is often in the 165K range.
ATC recognizes this and understands the fact that on some aircraft gear and flaps would have to be extended to maintain 160 knots on the nose, resulting in a larger noise foot print to those on the ground.
With that being said 164 knots has not been and still is not a show stopper for traffic separation with traffic 4 to 5 miles ahead flying 4 knots slower, which equates to a closure rate of 1 mile in 15 minutes… or 404’ per minute.