I've used the tenor trombone version of this straight mute for 20 years and I'm really happy that the bass trombone version is just as good.
There are no notes that suddenly don't speak as you expect, no strange tuning problems and very little resistance compared to the open trombone, even over a four-octave range down to pedal F and lower.
The sound quality is excellent and you can make it work well in a section using a mix of mutes from different manufacturers. Projection is noticeably good; complex rhythmic passages at quiet dynamics in particular are just as easy as without the mute.
The mute corks are large so you'll probably need to adjust them to fit the profile of your bell flare but that's quick and straightforward.
If you've used other mutes and been frustrated by the inconsistent response and poor tuning, this mute might be the answer.