I'm slowly but surely building my own stair models to put in our construction plans. There are some pros and there are some cons too but I figure, once I've got a stair model done, I always have it and its tweakable.
As for your pics digitalmechanics, you'd need some serious nurbs curves to do that. LOL They don't build them like they use to and codes don't allow for those old stair designs, short treads, railings and all.
But wouldn't it be amazing if you could push, pull and bend a stair design kinda like a subdivision object. So imagine you start with a straight flight of stairs with your min. and max. established but then be able to change the shape?
The stair tools needs a good overhaul.