I don’t know yet whether there’s something uniquely special to SPUs or I would enjoy just as much some low compliance 1/2” mount alternatives.
Definitely nothing special in GM E in my opinion, but the Royal with Replicant was superb in my system. The SPU Spirit is rare and unique because of the very special coil wire. There are so many different SPU, so i gave up.
Fidelity-Research FR-7f or PMC-3 or the rarest FR-7fz . they are great alternative to SPU. Highly recommended if you willing to try some other low compliance cartridges that your dealer can't offer :) Specs for the best FR models here.
A cantileverless Ikeda maybe ?
My cartridge of the month is Miyabi MCA