DD with enhance

G'day all, It has been suggested to me not to use enhance with a DD coil on my GPX 4500 as it effects the performance, Is this correct and if so why, cheers.

Its not that you cant or should not use Enhance with a DD...there is no rule when it comes to experimenting.

All DD coils have by design, an inbuilt ability to tame noisy ground no matter what timing you use. If you opt to use Enhance with the DD coil, you are doubling up on this ability to tame noisy ground. Is there a need to double up, thats the question.??  
You could combo the settings while using the DD coil.....Enhance + mono...this will give you back some sensitivity and maintain much of the DD coils ground canceling characteristics with the bonus of Enhance which is optimized for smaller gold at depth.
The trick is...use the largest DD coil you can swing, you now effectively have a large DD coil for use in the normal timings, and a smaller Mono coil to use in the smooth timings....Enhance/Sensitive Smooth.
Again, there are no rules, small DD coils in Mono mode will have their place also.

Awsome answer Narrawa !!!