Whew, that's an expensive swap you are considering Stan. Even though the Pentax is at an attractive price point, what you lose by selling the H4D/40 has to have an over-all impact I would think.
It seems you are not making a true comparison ... comparisons to the Pentax 55 and 90 should be the HC-50-II and HC-100/2.2 in lieu of what you are now using ... that zoom is indeed heavy and slower focusing due to the size of the glass that it's moving and dimmer max aperture. Selling the expensive zoom and 150 should pay for the 50-II and 100.
I can tell you that the new HC- 50-II is unbeatable, and the 100/2.2 is unmatched for selective focus work. Now there is a Close-Up adapter that's been optimized for the 50-II that opens up all sorts of new creative opportunities. These two HC lenses are my mainstay people optics. Both these lenses focus much faster than the zoom, and even faster than the 150.
As to over-all weight, the H body is 2 lbs more ... but I'd be sure to compare collective weight including comparable lenses ... after all, you won't be carrying the body alone
Be sure to compare viewfinder brightness using comparable lenses ... some S2 users thought their viewfinder to be brighter than the H camera's ... I have both cameras and put the same Hasselblad 100mm lens on both bodies and the H viewfinder is not only visibly brighter, it is more neutral.
I do a fair amount of outdoor portraits, and even wedding formals with the H, and I simply couldn't live without leaf shutter lenses, even just using fill flash ... it provides better control of the backgrounds and skies. 1/125th is just to slow of a sync speed for me on a beach or bright location. However, that may not be as important to you.
I've also found that the H camera can be usable at much lower hand-held shutter speeds than any focal plane shutter MFD camera, including the highly dampened Leica S2. The combination of leaf shutter and setting the mirror delay option on the H camera really makes a huge difference in available light.
To each their own.
Good luck which ever way you go. :thumbup:
-Marc