This is what I use my 135/2 Zeiss for about once per year, other than that it patiently sits in the lens drawer.
f/2 sometimes is not enough DOF at this close of range, so f/2.8 sometimes is used.
Hence my interest in the 125/2.5 CV.
Gorgeous photo ... and the resemblance is uncanny.
I find both the Zeiss and the Voigtländer are best at f/4, with the Zeiss being sharper then the Voigtländer @ f/2 than the latter is @ f/2.5.
Like you, the Zeiss sits around and doesn't get used as much. It's MFD (79 cm) and its only going to 1:4 make it more troublesome to use than the Voigtländer , which has a MFD of 38 cm and also goes 1:1.
Still, the Zeiss is good for certain distances ... as, for example, photographing a tired, sore doggy taking a nap after a long vacation.