of course 415 is separated from 400
In OZ, min 2000ft is separation is required from an aircraft at FL415.
An aircraft on climb from FL410 to FL430 is separated from FL400 as long as 1000ft separation exists while on climb and the appropriate separation standard exists when the aircraft reaches FL430. (2000ft) (Obviously both aircraft would be RNAV approved)
Separation should always be based on the greatest standard needed. FL415 requires 2000ft.