The Zeiss ZM lenses are fine quality. I've never heard of 'wobble', but all those I have used and owned have been quality performers with nicely weighted aperture and focusing rings. They are nearly all built in Japan by Cosina Voigtlander, but to much higher specs than CV lenses. But I don't think a lower price automatically means a poor build quality. The image quality is in most cases almost on a par with Leica, but with a different character to the rendering and colour signature. They also make lenses that are all about a unique character, such as the 50mm Sonnar, something that Leica dare not do for fear of losing the clinical look.