There are more problems than the rollingshutter On the A7s2. The codec is ok if you shoot in slog2. Slog3 will break it. Flashing lights or fast changing lights like in Clubs will break the codec. You will see some huge blocking artefact at the light change.

For ease of use I would shoot with an A7mk3 (better battery and ergonomy) or even better the A7s3 wich solved the codec problem.

My friend won the Swiss camera price with his film shot on the A7s2 and anamorphic this year. So it also depends on your skills. ;-)