I went to Bracken the other day to check out this seat. They had one in stock and very kindly fitted it to my bike so I could have a sit. It was actually a little higher than the stock one! The reason was that the padding in my stock seat had compressed - very common apparently. (I weigh 80 kgs and the bike's mileage is about 40,000). So I can't see any way to get a seat height lower than what I have now. Unless I were to buy the Touratech one, and it were to compress as much as the BMW one. I don't think that's likely because the Touratech one is very firm. So it looks like I'll be keeping the stock seat after all.
If a thing is worth doing, it\'s worth doing to extremes.