An ebullated bed hydroprocessing system is upgraded using a dual catalyst system that includes a heterogeneous catalyst and dispersed metal sulfide particles to hydroprocess opportunity feedstocks (i.e., lower quality heavy oils or lower quality feedstock blends) while maintaining or increasing the rate of production of converted products. The dual catalyst system improves the ability of the upgraded ebullated bed hydroprocessing system to accommodate and withstand negative effects of periodic use of opportunity feedstocks (e.g., without significantly increasing equipment fouling and/or sediment production). In some cases, an upgraded ebullated bed reactor using the dual catalyst system can hydroprocess opportunity feedstocks while decreasing equipment fouling and/or sediment production.