Hi,
i've just bought the Lite Version of r8brain and i would like to share my thought.
Well, the sound test is a soft ballad with little reverb and a very soft and clear drum ride going on with chorus armonization in the background.
The source is Float32bit/48khz, dest is Float32bit/44khz.
My test is done with high end DAW, headphone pre-amp, and SEN HD650.
I've done testing with the full demo-version with min phase, and i can say that indeed (as stated by the author) is "coloured", i can't say good or bad but mof not linear.
With the LinPhase and UltraSteep, the sound room appear "squeezed" or "smalled" with highs that jump a little up but i could say it "breaths constricted" and a little harsher.  The final result is that it sounds little emptied from the original "warmness" and more... "artificial"?  My impression is as if it sounds "less resolution" but "more highs".
The LinPhase without UltraSteep plays really better with little of high (inevitably) lost, but the warmness and the "analogueness" of the source is preserved.
So i can say i'm good satisfied with the result.
My 2 cents.

Thanks for your feedback..  Going from 48kHz to 44.1kHz is a tough comparison: I believe what DAC electronics may bring to your speakers differs a lot at these sample rates.