the two exist for entirely different purposes. unless im mistaken about the details:
1. by default, noscript runs all the js you enable, whether its freely licensed or not.
2. by default, librejs runs all the js that is freely licensed, whether its individually enabled or not.
so noscript runs js per-site and librejs runs js per-license.
but as i pointed out to someone higher up in the software freedom hierarchy than most (though lower than rms,) this does not make librejs a security tool. anyone can freely license malicious js and (i believe) librejs will run it. you can request it be fixed, but by then you have already run the malicious code (which could be on that site deliberately, or without the knowledge of the server admin.)
i must repeat i dont expect librejs to work differently than this. but it does require you to have two extensions fielding the js on each site-- unless the functionality is built-in to the browser.
most extensions are browser-specific, and if mozilla cared more about security than absurd strawman arguments about usability:
https://support.mozilla.org/en-US/questions/968821 "as for add-ons why disable something that you have to re-enable with a work-a-round sounds dumb"
yaaa! i lost a boatload of respect for mozilla in 2013, and it has never gotten it back again.
if not for nonsense like this, noscript wouldnt even be an extension-- it would be a browser feature.
no one should be surfing with global js on by default-- both because of security and also because of freedom.
the only thing alex limi cared about was convenience. i care about that too-- but not to the exclusion of all other issues.
also, im not saying that its necessarily better to have as a browser feature. if its easier to develop and maintain as an extension, great. though it might be easier to maintain as a browser feature-- if you are already maintaining a full browser like mozilla does, and not just making tweaks to an existing one.
then again if youre mozilla, the only easy thing to do is make your browser suck more every year, and perhaps also produce stupid excuses why youre doing that.
i do have some genuine hope for the local flavour of iceweasel, though i dont expect a miracle.
(posted from a lousy mozilla web browser, because most web browsers are lousy)