Nice extension, but a few hours after I installed it my browser became sluggish (click a checkbox, wait 20 seconds, the checkmark appears - that sort of thing). I restarted Firefox and then disabled the extension - I'm going to keep it installed so I can turn it on when I need it, but I don't need every single redirect all day tracked. I don't have any empirical proof that this extension was the cause of my sluggishness, so your mileage may vary.
A very useful extension for SEO, that is compatible with Firefox Quantum, thanks ! The interface is very well made. The only change I would make is not to state that 301 redirected pages are indexable, since they won't be indexed by search engines.