I've had such a bad experience with the macbook layering (touchbar too), I feel like it might be more hassle having to turn the layer on and then press the key.
Whereas with a dedicated fn row, it would be a lot easier. I'm quite happy with my adv2, but I can't wait for the reviews.
if the layer button is easily accessible, it isn't so bad imo. I have a function layer available just by moving my thumbs one button "inward" from resting position and I love it. It seems I like layers more than a lot of people though so *shrug.
I thought about this a bit more, and I'll give it a shot. I might see if I can contol my mouse using a layer (saw a person on youtube do something similar, but I forgot which video it was :/). That would actually force me to use the layers and see how it feels like in my daily workflow.