Stan, and all ... Yet even more random thoughts on this subject
It isn't easy to swap systems, and changing MFD systems is the "Mother" of all swaps.
Leica doesn't have any trade program, Hasselblad does. So the decision could also be framed as a comparison between the Leica S, verses the Hasselblad H5. Financially, the move to a H5 would be substantially less since lenses aren't involved. The H5 is not revolutionary, but has been improved in many incremental ways ... including better True Focus performance, higher capacity battery, faster interface, and new functional options. The cosmetics of the H5 are trimmer than the H4, and quite frankly a bit sexy looking IMO.
Lenses: To make full use of the S camera's dual shutter feature with Leica S glass, one would need to get the CS versions of the lenses ... which are still NOT all available. The CS versions are more money than the FP versions. (The current trade-in FP version + cash difference for CS lenses only applies to original owners who bought their S lenses before a certain date. Anyone entering the system now pays full Leica prices which are breathtaking, and there will be no used CS lenses available for a long, long time).
The S zoom is $10K and no CF version is planned ... same for the new S-24mm, no CS. The HCD 24 and 35-90 Zoom are leaf shutter.
A few other comparative thoughts (which are highly dependent on applications):
Macro applications: HC120/4 verses S-120/2.5: Chief difference here is the HC lens is 1:1 and the S is 1:2. There are no plans to make an Elpro adapter, or extension tubes for use with the S-120. There are 3 different extension tubes for the HC120.
AF speed in dull light ... I know the newer AF Assist light on the H4 has helped me a lot in lower contrast situations where there was no specular highlight or defined edge in the scene to focus on and recompose ... The S2 has none.
In low light/low contrast situations the S2 camera just informs you with a "Lo" in the viewfinder (when using AFs mode), and simply will not focus in Manual mode using the thumb button for AF. However, if there is any contrast point or defined edge on the same plane of focus as the subject, just lay the cross hairs in the AF circle right on it and the S2 will focus just fine. This especially works well when the subject is at a distance like with the Stuart's examples ... not so good if the subject is closer when re-composing ... which is where The H camera's True Focus really shines.
BTW, contrary to popular belief, the H4 viewfinder is brighter and more neutral than the S2's. I compared them by using the same 100/2.2 lens on both cameras.
Higher ISO: Assuming the H5/40 performs as well as the H4/40, ISO 1600 on the H trounces 1250 on the S2. I have not seen ISO 1600 files from the new S, so that remains to be seen ... hopefully it is improved.
ALL THAY SAID: IMO, the overwhelming Practical appeal of the S2/S not only lies in its handy form factor and Leica lenses, it is because
it is a dual shutter camera. To be able to shoot at 1/4000th with a fast aperature in bright conditions one minute, and at 1/1000 sync with strobes the next, makes the S2/S camera a winner in versatility.
When all is said and done, the unknown factor that enters the equation is ... LUST ... and few companies are as good as Leica in evoking pure lust, even to the abandonment of logic and reason :ROTFL:
-Marc