Imho, the BPK makes a difference, depending on the total brake pressure you use.
If the maximum brake pressure is set rather low in the driver, the default PU foam may work well.
When the maximum brake pressure in the driver is set rather high though, the original foam, being too soft, is fully depressed too soon, leaving you with a feeling of having no progression in the travel, and a brake pedal that has reached its mechanical end of travel, when you're still not braking too hard, and can apply more pressure still.
With the BPK elastomers, you can not fully depress the brake pedal anymore. With increasing pressure the travel gets progressively less and less, just like a real brake does. To what degree depends on how the 4 different elastomers of the BPK are combined.
I also have the impression, that the original PU foam gets softer over time, because I remember having been happy with the brake at first, but really becoming annoyed with the mushy feel after some months...
Not all is good though. It is quite messy and time consuming to disassamble the brake cylinder for exchanging the elastomers, until the right combo has been found.
I've fiddled around with it a whole evening, but not touched again ever since.