Here’s a looksy of what I have been getting up to recently, the Flex3Drive 2in1Duo - a dedicated Extruder/Hotend mixer combo where the two elements have been designed specifically to work together. Its very small and compact.
Have run all sorts of material through it, ABS PLA HIPS PET Flexibles, Nylon etc, and all without issue. Some torture tests have also been done including heat soak and standing hot starts.
Works easily as a “two colour switching extruder” without having to retract filaments, my focus has been on testing the mixing capability along with a couple of other nuggets soon to be revealed. The results are however pleasing.
Takes up less room than most other single filament whilst also mixing nicely, Black and Gold has been coming out a treat as do other metallic or trnaslucent colours:) It is based on Flex3Drive tech gives plenty of power and precision.
Shown is the printed version. There is also an injection moulded design which would make this far cheaper, but cost of tooling is the obvious hurdle. A shave under £20k from a local quality toolmaker its an option worth serious consideration. Only the main housing elements need to be tooled as I already have the geartrain tools and other parts.
Thoughts and comment appreciated. Why have a single filament extruder, when you can have dual filament in less space 
