difference between mono and dd on gpx series?

Hello guys.. someone can explain the difference bwtween mono and dd?

I know mono goes more deep and is more noisy with no discrimination.. the dd is more stable but less depth.. is that true?

A 18mono is more sensitive at little target (Relic hunting) then a 18dd at te same depth?

Someone can compare a dd and monos at depth? (some like 11mono=15dd depth).

Thanks!

Sure BetaGod.

It all depends on the type of ground you intend swinging over and/or detector/settings used. Mono coils can and will show superiority over a DD wound coil,over low to average mineralized ground conditions,but the moment a mono coil is placed over hotter sections of ground,it starts to behave erratically/noisy until the detector is dumbed down to accommodate the surrounding ground noise.This so called detector dumbing down is at the cost of sacrificing both sensitivity,as well as depth on targets,just so that one achieves a stable smooth running coil. A DD coil will need less dumbing down or should I say reducing the settings,such that of gain,to get the coil running smooth and quiet.
I have witnessed mono coils to lose almost 50% of their depth capabilities over the same size/type of gold,in hot ground,as compared to the same size/type of gold,found in quiet soils or lowly mineralized ground.
Both  DD and Mono coils will lose some depth to positive targets,as ground gets hotter or more mineralized in content, but due to the winding configuration of DD coils,I'v found the DD coil at times,to be on par or even surpass the depth of a mono coil of similar size,over the same size/type,in ground target.
Air tests give us some Idea of target depth/sensitivity,but due to the lacking of ground mineralization between target and coil (air space) should not be taken as conclusive evidence,as that when tested over undisturbed in ground target signals.
These are my experiences only and others here might have a difference in opinion.

Cheers Kon.