Posted by Monte
on 10/30/2009, 4:20 am, in reply to "5900 DI Pro vs Modified Classic ID"
24.21.38.127
There is no such thing as a "perfect" detector, although a new offering based on the 6000 Pro XL / XL Pro with selectable Auto-Trac or manual Ground Balance would have to be very close. 
The 5900 Di Pro SL (like the 6000 Di Pro SL or XL Pro) can make a great "cruising" detector as it CAN be swept at relatively fast speed and not lose performance, even in highly mineralized ground. At the same time, with a high Signal Balance setting, they MAY be swept reasonably slow, especially with a smaller coil like the 6½" diameter group (Blue Max 600, 5.3 Black Max, 5.3 BullsEye).
While the Classic series models, such as the ID/IDX/IDX Pro, with Bill Crabtree's modifications provide for great operator control over the unit, their 2-filter design is still a dedicated, typical-performing slow-sweep design. At it's best when worked slowly, it seems to provide excellent performance for the patient detectorist.
In low-to-moderate ground they can be swept a bit faster and still work fine, but not like the 4-filter types. In higher mineralization they CAN/WILL lose responsiveness if swept too quickly.
An 8" coil, as you suggest, is an okay general use coil, but isn't the greatest in heavily littered sites. In "dense trash", a slow-sweep coil presentation will be best, especially with a smaller-than-stock coil. Of the types you mention, the Classic model with a 4" or 6½" coil is tops. In more open areas with a low target count where faster coverage is required, the 5900/6000 Di Pro SL or XL Pro with an 8" or stock 950 would make the much better choice.
Personally, I am not all that excited about Double-D (wide-scan) coils and prefer a proper-size concentric for most applications.
It's not a matter of which of these two model groups is "better" as much as which one is "best for a certain site."
Monte[/b
Responses: