I just replaced the U4K prom with the Eureka one and messed around for a while.
From my point of view the Eureka is more user friendly.
I am able to turn on & off all the stomps and all the effects, instead of having to go back to the KPA, as I had to with the U4K. I can also assign the left expression pedal CC assignment (almost) on the fly, which again I find very handy.
Additionally, the other modes offered (Fav presets, Specials and the split mode) will find quite a few fans.
I'll be playing quite a lot the next couple of days and I'll have a better idea of the overall functionality after the weekend.