Re: the DA 12-24 f4.
Over the past few years, when Pentax brings out a constant f4 zoom, it has been a signal that it is a serious lens (e.g., FA 20-35 f4; DA 16-45 f4). This was an early indicator that the DA 16-45 was going to be a good lens, and was a major factor in my decision to buy a D even months before the lens was released. If the DA 50-200 had been a constant f4 I would have had no reservations about it.
Joe
