What is the most cost efficient way to transfer larger amounts of money (70k+) from a local SGD bank account to a bank account outside of SG?

You can try Transfernow which is base on how much you transfer as well as it has better exchange rates which I have used so far. It is cheaper than M1 Remit and safe too. Your destinated account can received the money on the next working day.

But in order to prevent money laundering, it has some step by step security features to follow.

You can use my referral code below to get a free transfer for the first time:

https://transferwise.com/invite/a/leel364

Let me know if you have any question. :)

Cheers.

Stuart

I haven't explored it yet, but it seems that TransferWise is garnering positive attention. Also, my friend who is currently working in Japan swears by TransferWise. There are 38 TransferWise reviews on Seedly - check them out: https://seedly.sg/reviews/remittance/transferwise