From my personal experience as an dx'd adhd person with informal autism dx and one child with dx'd AuDhd: Many experts I talked with said that in practise most people tend to be AuDHD. Often with not enough symptoms for an formal autism-dx, bc the ADHS can hide it very well.
Personally I can relate with AuDHD people and people with ADHD-I even though I'm myself are ADHD-C.