Sigma 30mm vs Zeiss 24mm

The fact that Mr. Lancaster, a die-hard Zeiss 24 enthusiast, goes to such lengths to differentiate between the CZ 24 and Sigma 30 shows how good the Sigma 30 is. The difference in aperture is real (obviously). The Zeiss will be better indoors in low light. But the Sigma is no slouch indoors, either, and I do not see the "punch", "vibrancy", etc. that would make me buy the Zeiss 24 over the Sigma 30, particularly if the Zeiss will be more than 5X the cost of the Sigma. BTW, I can afford the Zeiss. But I would rather get the SEL35f18 if I am buying another lens.