The price difference largely depends upon your specific wants and needs. Here is a simple comparison of the advantages of the two as I see it.
Caly 3.5 Carbon Fiber
Hitachi ZDP-189 steel cladded in 420J2 (laminated) blade offers greater edge retention than VG-10.
Carbon Fiber scales are more elegant looking and far less prone to wear out pocket fabric than more abrasive G10.
Caly 3.5 G10
VG-10 blade is easier to sharpen than ZDP-189 and less prone to scratching than 420J2 cladding.
G10 scales provide more secure grip than carbon fiber.
Street Price $20-$40 less than carbon fiber version.
Looks aside I think it boils down to how much cutting you do and what your sharpening skills are. Mountain lions fear both versions equally.
Not to confuse things but there is also a Caly 3.5 G10 (Grey) Aogami Super Blue Sprint version that is discontinued but frequently available on the secondary market (forum exhange, ebay, gun shows, etc.). The street price of a user in this version is closer to a new ZDP version. The blade steel is premium high performance but not stainless and thus requires more maintenance than the other versions. This is my personal favorite of the 3.