Well I think it depends on the installation. Once I saw LED Exceders in a restaurant that had reclaimed wood walls, and when I first walked in and saw that they had an ANN-80 and BG-12LX’s I was at first confused because I didn’t see any NA’s and thought they didn’t have any. I looked around and eventually spotted them, but it was really hard to tell there were any NA’s there. They’re pretty low profile to me (I have an LED Exceders in my collection, and it’s only slightly larger than my hand). I don’t think there will ever be any ‘true’ unnoticeable NA made because these NA’s have to be pretty noticeable during an emergency situation as well as to alert the hearing impaired (and maybe even wake them up at night). I just remember that fire alarms are fire alarms and are designed to be noticeable, not to improve overall building aesthetics. My school has the super boxy 2903’s and 4903’s from the 80’s-90’s and after a while, while they’re definitely not low profile, you don’t seem to notice that they’re there once you get used to the building. So I think there’s upsides and downsides to both low profile alarms and very noticeable alarms.