Specifically, does Neat version 2 support IE? Is it tested in IE/Edge etc? What other browsers are supported or not supported.
You should be absolutely fine - the only major feature Neat uses where there may be some support issues is calc
. See this post in the issues:
https://github.com/thoughtbot/neat/issues/631
And information about browser support for calc
here:
https://caniuse.com/#search=calc
I have tested in IE11 and Edge with no issues