I borrowed one last Saturday for the day, running it on my 4500.
I found it very noisy running in Normal on Inkerman Vic GT mineralised ground. At the start I was digging mineralised ground that sounded like a deep target. Had to back the Rx off to 7 and Stabiliser to 8, Quiet Audio, and running it in Medium Tracking made a big difference. On these settings it was usable but still a bit chatty. It was much better in Enhance, but that to me was defeating the theoretical potential depth gain of running a DD in Normal.
I tried it because I wanted to compare the DD 25 X-Search in Normal versus my 19 Evo in Enhance on mineralised ground, thinking the DD may handle it better. Ill stick to the 19 Evo as it performed better, in my opinion, and is a hell of a lot lighter for my poor old back.
Oh, and the 25 DD is a little too big for the shaft and wobbled around and felt unstable. In fact the bolt that came with it was stripped from people before me over tightening trying to get stability. Fortunately I had another bolt and nut to use.
This is purely my experience and opinion and leave everyone to have their own. Cheers