There IS a fix for whatever is causing a mismatch between Photoshop and C1. Sometimes color management issues can be hard to track down (especially in Windows and especially when you have more than one monitor), but I can assure you on a properly running machine the color will match perfectly.
Doug, hate to disagree here.
Basically, yes, the color management in C1 is totally up to the task and basically colors of the C1 preview and the processed TIF viewed in Photoshop match (as I have demonstrated here some time ago with this layered tif:
http://tinyurl.com/36k4n8e ).
The C1 color management is as good as the systems color management as C1 refers to WCS (on WIN) resp. to color sync (on MAC).
BUT...: Adobe uses "black point compensation" for the translation to the monitor profile. Now, if the monitor is not calibrated or if you use the monitor profile provided by the monitor manufacturer (or the system preset on MAC) you won't notice the difference as in these profiles black is L*0. But if your monitor is calibrated (it should be, shouldn't it?) and the measured black point of the display is not L*0 but L*2 or L*3 or whatever ... which is stored in the monitor profile (!)... then you will see differences as Adobes black point compensation handles those values differently. It only affects dark tonal values, in particular, well, the blacks. But it is clearly noticable, especially in images that contain large shadow areas. (You can't even change this behaviour when you switch the color management module in Photoshop from ACE to the respective system CMM... as Photoshop, all Adobe softwares, always use the internal Adobe-CMM for the translation to the monitor profile).
Strictly speaking C1 does it right and Adobe does it different. But as Photoshop is the de facto standard in imaging software (and BPC is a brilliant feature) it would make sense to introduce an option to switch the CMM in C1 so that we can utilize "Adobe CMM". I was asking for this feature since 2 years or so ... but obviously only very few people ask for it so it's probably way low on the priority list at Phase One.
edit:
here is an example...
image viewed in "preview" (above), "C1" (center) and Photoshop (below).
Monitor with the default system monitor profile (black is L*0).
Preview, C1 and Photoshop match:
http://drop.io/gbu95jz/asset/werk-jpgthe same with the monitor profile based on the actual calibration (black is L*3).
Preview and C1 match, Photoshop shows better differentiation in the blacks
http://drop.io/gbu95jz/asset/cal-jpg