Still curious about them, regadless of my prior experience, I purchsed one and had it for about three months.
I used it on several different basses. Tuning was not 100%, but it was close, maybe a slight tweek on the scroll end. More than anything, it adds mass behind the bridge. Some bridges respond very little to mass in that area, so it was fairly normal sounding. Other, more sensitive basses it was pretty obvious amount of muting / dampening.
I can't speak for ease of installation, mainly because almost every bass I touch seems to have some small inconsistency, so I automatically pick up the tools and make a few tailpiece tweeks, et cetera.
One thing I do like is that loosening a string to lower the tension is very different than using a longer scale ( like an extension) that keeps the same tension but you go lower down the string to achieve the note. For my needs and preference, lower tension to crate the note is much better. All of my basses seem to open up significantly and bloom with a dropped D note, so much that a couple of years back I built a nice new neck with a nice extension for myself and within about three days, I chopped it off and went back to using a dropped D; 'still happy to this day.