Matter of preference, Green address is good but I'm a core user although I didn't notice they used multi-sig
Although the only exchange using 3 sigs is bit-x to my knowledge so did have a relative knowledge it was being used but didn't see it for users only.
Thanks for the link
no also
https://www.therocktrading.com/ is using multiSign address ( if I'm not wrong).
I never heard of them but your correct
Were pleased to be the first european exchange to support both multisignature and instant confirmation. Our users will be able to store their bitcoin in the most secure wallet, while instant confirmation let them being in control of Bitcoin funds until the last moment. Its another step toward exchange trust.
It's good to see more exchanges using this though reduces the simple risk of 1 key being broken into.