I used FF for years, then due to the constant changes lately, I switched to Chrome, and now, after FF 57 was released, I was eager to test FF again to see if it's worth to actually come back. It's in Chrome that I first came into contact with uMatrix, looking for an extension similar to NoScript. Seeing that there are many users here who switched from NoScript as well, I thought to re-post what I posted back on Chrome WebStore, regarding importing a long whitelist from an older version of NoScript - maybe it helps someone:

Below you have 10 easy steps to import NoScript's Whitelist into uMatrix (especially if that list is long - like mine was, since I came to Chrome from Firefox):

1) export NoScript's Whitelist to a text file, from within NoScript (if you didn't do that already)
2) edit that textfile using Notepad++
3) select all with CTRL+A
4) click Search/Replace from the menu and tick Regular Expression
5) type "\n" for "Find what:" textbox and " * allow\n* " for "Replace with:" textbox (without quotes, but including spaces)
6) click Replace All, close the dialog, modify the first and the last line in the list to match how the other lines look, then copy the modified contents of the text file again, using CTRL+A
7) go to My Rules tab within uMatrix's Options (Dashboard)
8) click Edit in the Temporary Rules column
9) paste the text you copied at step 6) at the end of the already existing temporary rules
10) click Save, then Commit in the Temporary Rules column

That's it - now you have the whitelist from NoScript into your uMatrix extension. You can then make any further modification to the settings in that list on an individual basis, which is much easier than having to rebuild that list from scratch all over again...

RESPONSE TO THE DEVELOPER:

I wasn't aware that you can directly import those rules when I first wrote this review back on Chrome (27.07.2017), and I didn't know whether you provided the functionality right from the start or it was added afterwards, so I assumed that you can't directly import those rules from NoScript - hence my reviews.

On the conversion type, those are just my preferences, especially given the way NoScript interprets them (i.e. general over specificity for a domain), maybe others prefer them to be a little more restrictive - that's why I said that you can make further adjustments afterwards, on an individual basis. Personally, I need frames to be allowed too on most of the whitelisted domains, as they provide functionality I sometimes need (think streamed media, for example), thus, from my POV, there wouldn't be much difference between a broader whitelist rule and allowing images+css+script+frame (it's allow all vs allow almost all). Bottom line, it might be better for regular users the way you designed it, since it's preferable to be more protected over allowing all and make some mistakes. Me, I know what I'm doing, so I can safely go with all or nothing style.