IMHO they aren't small Navi and they aren't big Navi either
They are the "just right" Navi twins hahaha
To be clear, I have no more information on Big Navi than anyone else, but if it's better than Prospero GPU, then Holy Shit.
The rumor for big PC GPU Navi is 80 CU it means 20 Tflops at 2 Ghz and with raytracing and other feature like VRS. The rumor begins last year.
EDIT: The big PC Navi GPU will be a real monster.