We use VS with caution at high levels to prevent the machine chasing 1 or 2 knots with large variable rates of climb just before ALT capture.
It's necessary to use VS intelligently so as not to loose speed. In order not to have thrust reductions (should we momentarily exceed the required speed) we select a higher speed in the ATS window.
300 ft per min ROC approaching Optimum ALT is not unusual.