Multifunctional reactors have been in existence for over 50 years, but only 15 years by name. Despite extensive research and innovation in their form and use, the number of commercial applications remains relatively few. This paper explores the diversity of options and extent of multifunctionality using synthesis gas and hydrogen manufacture as an example. Integration concepts include coupling of exothermic and endothermic reactions, heat exchange reactors and reactive separations. It is noted that those that have been commercialized have only a limited degree of integration, with the various operations frequently spatially separated. The evidence from this is that higher degrees of multifunctionality and integration inhibit commercial implementation. This suggests that many of the potential benefits can be achieved by a partial approach to multifunctionality, and that further integration has a low incremental value. Two further case studies are used to explore this hypothesis: toluene disproportionation and regenerative heat transfer for methanol synthesis. Both, for very different reasons, point to an optimal approach being the partial disintegration of multi functionality, using systems such as a reactive pump-around as an approach to reactive distillation, and well-selected configurations of heat exchange reactors in lieu of regenerative heat transfer. The conclusion is that one should use multi functionality only up to a point. Multifunctionality need not be an 'all or nothing'. Significant benefit can be achieved by selective and partial multi functionalization and development should explore the opportunities to achieve this in addition to the studies of total multifunctionality.