The quantity and location of nozzles are based on an engineering analysis of your particular pool, and a certain water flow (i.e. pressure head) is required to make the system work as designed. Well-designed IFC systems have dedicated pumps for optimum performance. This keeps the filtration loop separation from the floor-cleaning loop, so there is no variable pressure drop as the filter media get dirty. Right now, I'm running my filter/SWG pump 6 hours per day, but my IFC pump only runs for 1.5 hours each day, which is sufficient to keep the bottom of my pool completely clean. I'm 100% happy with my Paramount PCC2000 system.
As a satisfied customer, I am also a strong advocate of these systems...as long as they are properly designed. Unhappy folks fall into 2 categories: They either don't know how the system is supposed to work (there are a few counterintuitive particularities in normal operation), or they are unfortunate victims of a poorly designed system. The additional pump is definitely an indicator of a well-designed system.
And then there is the convenience factor. Once a week I empty the basket in the debris collector, which can be accessed from a skimmer-type cover at my pool deck. I don't have to put in and remove a mechanical roving cleaner when we want to use the pool, and the increased mixing ability allows me to rapidly dilute chemicals as I add them. As for durability, there is a lifetime warranty on nozzles (which can be user-replaced in about 2 minutes), and the manifold has very few moving parts that can be quickly and cheaply replaced.
To succinctly answer your question: If you want the IFC, the extra pump is a necessary requirement for optimum performance.
