I bought a redeemer and have been testing it out. I put it in the box shown in the attachments so I could try it easily on different systems and do some A/B testing. I do not have golden ears, so keep that in mind
I tested the redeemer in my normal setup, bass->active DI->mixer->headphones, plugged straight into the mixer (no DI), and into my iAMP500C. I tested mainly with a P bass with flats but I tried some other basses too.
The redeemer has a bit of a volume boost, so it is hard to A/B it. There was a slight difference in sound, but that could be just because of the boost.
I don't have a lot of experience with active basses, but I have found they tend to give a slightly hollow sound to basses with flats. The redeemer did not do this. It was very flat to my ears. So don't ask for sound clips, you won't tell the difference with 128k mp3s.
The redeemer worked as expected in all situations. Without the DI, a passive bass loses some highs in the mixer. The redeemer made the DI unnecessary. I also ran it though 45' of cable with no noticeable loss of highs.
As a bonus, with a passive bass you no longer have the treble bleed problem.
It works without a battery but there is a noticeable attenuation. With a very dead battery (measured 1.6V no load), I got distortion.
So will I be installing the redeemer in one of my basses? Probably not. I don't really need a buffer and I don't want to deal with the battery.
Would I recommend the redeemer? I would. It provides a very clean buffer for a low price. And it can be run without a battery if required.