I use the 816 only for external hardware and do not find it noisy. But I can adjust most of the signal on the hardware gear and I reach out for a point (mix of hardware output and levels on the 816 or in Cubase ins-outs) where there is the least of noise.
I also tested the 3th Gen Focusrite18i20 and did not hear any noticable difference. Maybe the 3thGeb is better, I don’t know.
I did not choose it because of the software mixerposibilities.