I swung an AT Pro for maybe 30 seconds some five years ago, and I've never seen a Nox in person. So I can't tell you how the Apex would compare to either of those machines.
With that many targets in the ground (signals driving you crazy) I doubt any machine will get a lot of depth.
The Apex has iron volume as well as iron audio. The user can choose if they want to hear iron, or not, and how loud that iron tone is. In any mode but Zero Mode, pressing the iron audio button will let the user hear the iron tones. (Don't use the iron audio button in Zero mode - it makes good targets sound like iron). I normally hunt in Zero mode or Relic mode, with iron volume set to 2. If I'm in Relic mode (or any mode other than Zero mode) and I want to check for iron - a simple press of the Iron Audio button and I can hear any iron that is under the coil. Press the Iron Audio button again, and no more iron tones.
With the recent update the Apex does appear to have a pretty stable target ID - although that can bounce around a bit if there are other targets very near. Over the weekend I dug multiple targets with all sorts of trash in the same hole. Some had nails above and below the good target. Some had trash right next to the target. One hole had 3 dimes, 1 penny, 4 nails, and a screwcap in the hole. I dug the hole because the Apex gave me a repeatable high tone. I have no idea what the target ID numbers were - I don't pay them much attention.
The Apex separates very well. The areas I hunt tend to be very trashy - with everything from bits of 200 year old iron to square tabs and foil. I do prefer using the 5X8 coil (Ripper) but I think the stock coil (Viper) is quite good too. I have not done depth tests - I just hunt my sites and get whatever depth I get. The deepest target I've dug (Apex) so far is a Ford vehicle key that was 7-8 inches down (in a trashy area). I believe the Apex will easily hit a quarter at 10 inches - and possibly a couple inches deeper than that - but have not dug that deep.. yet. Some of that will depend on the soil, the alignment of the moon, etc.. The depth will also depend on the amount of targets in the soil - a lot of targets and chances are I wouldn't hear a really deep signal anyway.
The Apex is a very well made machine. It is easy to operate, yet offers enough adjustability to make it a good machine for most hunting situations. The headphones are fantastic - perhaps a bit warm on hot days, but the audio is excellent and I cannot discern any lag. I like the tones of the Apex (the update altered them just a bit). The Apex pinpoints well. It is very light weight and easy to swing.
