AP you are working for the enlightened and thanks for your post. The 125 series aircraft is descended from the Dominie I think which was originally used as an instrument training aircraft by the RAF. When it was used by them it almost always did a flap zero take off because, as you say, its already clean that way and the 2nd segment climb is better. Bizarre then that when its used as a business jet the SOP's get fannied around with and it becomes the norm to take off with flaps set at 15(I think). And then, because the dolt that has written the part B has copied it from someone else, this confusing rubbish about 1500 feet gets thrown into the equation. I advocated taking off in the CJ flap zero at my previous employer and got all sorts of snipes for being experimental.
Nobody want to take the 100 quid bet? I'll up it then to 200. Flight Safety instructors particularly welcome..