Just finished looking at an EOS R with RF 24-105 L IS. Held in size 9.5 hands it's compact and dense with excellent perceived build quality, neither the body nor lens felt plasticky. It's all very solid and of a piece. But far as the sizing goes I would not want it to be any smaller. Thankfully the hand grip is up to Canon's high standards which keeps it feeling secure. I found the EVF very clear and crisp, with enough resolution to easily focus manually on the finer details of a subject without using its focus magnifier or focus peaking features. Functionally, it was like focusing on a high quality matte screen and that exceeds my expectations by far. I bet it will be delightful with adapted MF glass! Color me impressed.