If you want more versatility, then go for the 32ohm version - this can be powered by portable devices, and larger amps too to a certain extent.
The higher impedance headphones require greater voltage swing to work properly, and require larger amps. I'd say the benefit of higher impedance headphones is better matching with larger amps and studio gear - these have an output impedance which is higher than portable gear. Generally it's recommended that the amp's output impedance is no more than an eighth the impedance of the headphones, for a good sound.
Maybe check the output impedance of your piano and go from there.