Sigma 30mm f2.8 or SEL 35mm f1.8

I read many threads in this forum about how sharp the sigma is. however, many complained about the slow autofocus.

so i decided to wait for the sony E-mount 35mm f1.8 which will be released(as per sony) on 23.12.12 for 450$ compared to 200$ for the Sigma.

so am I thinking right ?