I've just found a link to the dev version of Microsoft Edge browser for Mac. For anyone wanting to give it a try and test out their SD websites on it the link is:

https://t.co/T35gz9kpAI

Seems to be stable and runs quite well for me. I haven't found any issues yet but haven't tried grid on it yet either.

Thanks.
Looks good on my MacBook pro. No problems so far, including previews in SD V3.5 with grid based projects.
I am not going to do extensive beta testing though, but is already now useful for quick compatibility tests