There's a major difference and compromise, clarity and high frequencies will be compromised with any attenuator.
I compared a Suhr ReactiveAl Load vs a real speaker load with one of my amps before buying one and sold my Grossman Isobox becase the Suhr sounds awesome. All reactive loads sound different and they have different impedance curves, but the same happens with different speakers.
I sold my KPA and now I'm using three tube amps with the Suhr.