My guess is the instantaneous failure during take off and initial climb (flame-out, engine separation, severe damage) is by far the more critical in terms of handling - particularly with severity of yaw and probability of overcontrolling (spoiler activation). If you can cope with these type of engine problems satisfactorily, then "slow" engine failures would be a non-event. For example a flame-out of one engine just as take off N1 has been attained usually around 25 knots), requires fast reaction by the PF and by the captain if the PF was the first officer.
Be careful if the instructor fails an N1 gauge during the take off run near V1. I have observed a crew member calling "engine failure - STOP" when the N1 gauge was failed and the captain aborting the take off...because he reacted on the call without confirming first that an engine had actually failed or not.