IBIS with EF Lenses

[AlanF]

Is my impression (which I think I got from reading this here) correct that IBIS is more effective on shorter lenses than on long ones?

That's always been the case, yes.

 

[nc0b]

Is there any IBIS benefit using the R5 with the EF 400mm f/5.6 lens? If there is any stabilization improvement, does it show up in the EVF?