Add to that WiFi, an articulated screen, small & lightweight body, and you have quite the FF body. Oh, and let’s not forget focusing down to EV -3 (for all AF points), which puts it ahead of most, if not all, other DSLRs in this regard. The A7S does focus in lower light, but b/c it is CDAF which already tends to be slower than PDAF, and b/c focusing slows down in low light, the reality is that focusing on moving subjects in such low light proves rather difficult for the A7S (and many others, really).
The top downsides that come to mind are that the buffer fills up very quickly, and 1/4000s might be a limit for some. But these are some hardware-level differentiators – and there have to be some differentiators across products in their lineup, no?
Started out doing photography at the age of 6 using an uncle's old 1940 kodak brownie box camera. At 15 years of age, I decided to buy my very own 1975 Praktica SLR camera. I now shoot with a Nikon D850. I do unpaid TFP and commercial paid work.