The mileage on my trans is in my signature, 110K. I just bought the car in late October and I don't know the transmission's history. I have no evidence or any word on what has been done. It seemed like the original fluid, but I'm not sure. (There was none of that typical trans fluid smell, just smelled like hydraulic fluid. No burnt smell to it either) It was driven nicely I would assume as it was women driven, but I guess not all women drive the same lol. If I knew exactly what was printed on the oem filter, I may be able to tell is it's oem because I still have the old filter.
On flushes, I'm not sure if it's just the difference in the old/new fluid, or the fact that the machine used to flush may have pushed some particles around and did more harm than good. My old fluid looked pretty good, and was about the same viscosity as the new fluid, so I felt pretty good about that. My flushing method is completely natural and will not disturb any particles in the transmission and do possible harm like the machines may.
The magnet in the pan will always be coated with the clutch material, even after 30k miles. Picture #6 shows my magnet. There's a decent amount of material on it, not something I should be worried about, especially if it's original. If it is the original fluid, that amount of material is a good thing.
My trans is shifting better than it was before the service/shift kit, so I believe I'm in the clear. But going past 120-150K miles on the original fluid, and changing it does pose much greater risks.
I wasn't sure if I wanted to include information about that in this post or not. I really didn't want to put anymore than maybe a sentence or two because its just a how-to on a shift kit installation. I would say if the fluid is dark, that is clutch material and are those particles you were talking about. They have "scarred" the transmission, and are keeping it working because they resist the flow slightly(keeping pressure up). My trans fluid was still red so you could tell it didn't do much scarring like a brownish or dark brown fluid does. All I can say is make sure to disconnect the battery so the transmission can relearn the shifts and pressure related. I may make that text in red to show it's important.