Hi, glad your having fun ...
What changed me from Conc to DD coils was a hunt for modern shallow coins with a friend
He had a DD on , I had the standard MF Concentric
I passed over a signal which sounded terrible / very scratchy and not like what we had been getting ( nice clear mid to high tone ...Australian modern coins)
My friend came along after me and seperated and picked out about 4 modern coins which were about 1 - 2" apart
When he asked me why I passed over that spot I explained what it happened.
We put the targets back down in the places where he dug them from and I unplugged my headphones so he could hear and swung the Conc. coil over them
he said " Oh , I see what you mean sounds crap ! I would have gone past a signal like that too".
I got him to to that with his DD coil so I could hear ...result was clear individual signals and TID numbers .
I went home put a DD coil and the Conc. now gathers dust.
Yes, as you have experienced....generally speaking Conc, coils are commonly known have the most accurate TID no's between the 2 coil types
It is a matter of preference though, DD or Conc. ..... some like one or the other , some use both types.

T59