@p7ast1k I took some pics for you and
@Mercatino who asked me for info privately.
I used this photo from Xing as a reference, which may be valid for older CFs, a little less for new ones:
So I tried to compare Clean, VSF, Deep and BTF crystals with the same light pointed above:
CF Bluesy 41 and VSF Sub 41:
Cf Bluesy:
VSF Sub 41:
Thickness and edge difference:
CF Bluesy 41 and VSF Sub 40 ((All almost very similar to the crystal of the model 41):
CF Daytona with Deep installed and VSF Sub 41:
CF Daytona with Deep installed and CF Bluesy 41:
CF Daytona with Deep installed and BTF Daytona:
Thickness and edge difference:
@Mercatino here I tried to superimpose the "original" CF xtal on the Deep mounted on the Daytona (which, as I told you, will be removed):
In conclusion, in my very personal opinion, for the Sub 41 VSF or CF there is absolutely no need to install a Deep, except if you want to highlight a particular dial.
For the Sub 40, the xtal VSF is much sharper than the CF (I had to fix one for a friend of mine and it was definitely foggy on the crystal).
For the Daytona, the CF crystal is really acceptable, the BTF is the one I prefer for the more "classic" models, the Deep I will use on more particular projects...let's not forget that the Deep disappears in sunlight, an effect that can be very pleasing, but it distances itself from the Gen feeling: