Anyone who has been around the forums should expect me to promote my own favourite, the PZ-1 or PZ-1p.
I am not familiar with your beloved ZX-1 to know if it is fully compatible with all pentax lenses, but the PZ-1
is
The PZ-1 is essentually a film version of the top end DSLRs. (*istD, K10D, and now K20D)
It offers center weighted, matrix and spot metering, a 1/8000 shutter with 1/250 flash sync, TTL flash, full functioning with every lens except the newest HSM motors, (PZ-1 is screw drive AF) AF speed is good, and sensitivity is excellent.
Like you, I am costantly looking for the image preview on the back, I like the idea of a mirror
and might try this.
I have tried it with my one and only digital only lens (sigma 10-20) and there is vignetting at focal lengthhs of 13mm and below, but otherwise the lens is functional. It can also use FA-J lenses which is a benefit, and if you can find them, the PZ-1 (PZ= Power Zoom) can work with specific lenses, and the predictive autofocus, plus the power zoom to keep the image sice (at the focusing point) the same by changing the zoom ratio of the lens as it tracks focus over changing distance. it is really good for sports inthat respect.