Hi, all things said are true, you alone decide.
This is what I think: it is harder to save up for the da15, as it is more expensive. To add a da40 afterwards is easier than the other way around.
Most of all: da15 shapes the land and the city and the partyhall and the museum and the people right in front of you, it is an inspiring lens that takes you anywhere. With it, you step into a new dimension, just do so, think differently, think da15.
I love landscapes, with any lens, upto 300mm. But 300mm is somewhat limiting, da15 never limits.
Well, what else to say, you decide. But it is so comfortable a lens and .... No, I stop. Maybe it isn't your thing, I doubted it at first too, but well, now it is always with me. Except when I go Takumar. But that's a whole different story. Have fun with whatever it is you decide to have.