Definitely a great camera if you have the spare cash to splurge! Personally I've found it difficult to beat the Canon 6D (Mark 1) for low light AF, even the MK2 couldn't match it! The mk2 had slightly better high ISO performance, but only marginal really. I've not used the A7 RIII specifically but I have tried other Sony's an as yet, I've always found mirrorless to lag slightly compared to DSLRs. That said the future is definitely looking very Sony at the moment!