I want to try making IMBC for the first time except my bench mixer only uses a plastic bowl...would this be ok or does it have to be the metal ones because of the heat of hot sugar syrup being added?
You really need a metal bowl if you want this to work right. Plastic holds on to residual grease. You can't have any grease on anything when working with egg whites (meaning, whipping them). Not on the bowl, not on your utensils. The hot sugar is not going to melt the plastic, it's going to cool when it streames into the egg whites.
Just an update that i took your advice and REALLY gave it a good double wash and rinse and had no probs with grease and the IMBC came out great