What is different about the HPX170's lens other than it's smaller thread size and wider/less telephoto? I didn't see the Leica logo on the lens shade, is it manufactured by a different company?
The lens looks/feels/acts exactly like the HVX/DVX lens. It's the same Leica Dicomar design.
The bayonet does match the DVX's bayonet.
The widest possible aperture, at full wide angle, is 1.6 across the board. At full telephoto, the 170 & 150 are f/3.0 instead of f/2.8.
At equivalent focal lengths, the 150/170 or 200A will have slightly shallower DOF than an HVX200, because the chipset is about 7% bigger. But the 200 has more magnified telephoto, so -- meh, it probably nets out about the same.