For the RV-10 the FWF kit is an excellent and complete package. You can certainly buy hoses from different sources, omit the prop gov if you've already got one, etc. The kit contains all the big parts (oil cooler & mount, prop gov, exhaust, Filtered Air Box,etc) along with virtually all the small parts (hoses, fittings, hardware, etc) and also includes the plans set.
Unlike the 2 place RVs, there's essentially only one supported engine option for the RV-10: a parallel valve 540 size Lycoming. That allows them to put together a more complete package and instruction set.
Bob