We were looking for the fastest way to speed up multivar series in Pynac and the thought process started with what Nemo is doing, ie leveraging flint types. Now to completely implement what they are doing in C++ is likely too much for the student since he also has univar on the plate, so I thought maybe this can be shortened by using Piranha as generic layer. But independently it's an interesting idea. Of course there is still the option to simply use Piranha only but maybe there are benefits from a poly type. Did you compare the fateman benchmark yourself on one machine (silly question I know)?