The body is a little smaller and lighter than my 5D4. The EF glass though I think was smaller than the RF glass. Thankfully with the adapter, they work better than they did on the old DSLR’s. No MA needed. Seemed like it got a lot of bad press in the beginning, but it’s gained a lot of respect now.
Did some Googling - fractionally larger and heavier that the Panasonic G9, which is currently my main camera. Although in saying that, I really loved using the M5 last week. So light, and I could carry it, and two lenses in my work bag - had forgotten how fantastic that the kit is for carrying around.
No money for GAS at present, but perhaps when the next model EOS R comes out I might pick up a second hand of the original one.