You're pretty much in my situation, my cartridge was ZYX Airy-3 when i decided to try SPU first. If you will start from the entry level SPU i'm pretty sure you will not be impressed at all compared to High-End Lyra Cartridge. My ex ZYX simply killed that SPU in dynamics, extended frequency range, clarity etc etc. Everything was much better with ZYX, compared to the entry level SPU. I realized pretty quick that it was just a waste of time and money, but at least i tried the thing that people call "musical cartridge", if fact it was so boring, and when i was thingking about 4g tracking force i was worried about my records. Personal experience is important with everything we would like to use in our systems, i sold that conical SPU here on audiogon and lose money on it, but i gave it a second change and bought Spirit LTD model.
The Spirit has very rare 9N copper coil wire and that's why it's limited to 500 units only. It was much better than conical SPU classics for sure, but still not refined as the modern high end cartridges.
Royal G MKII is better than Spirit. Replican 100 stylus of the Royal G MKII require less tracking force than all other SPU models. And this stylus profile can extract everything from the grooves if you can set it up propertly (VTA is very important). So it is worth the price difference if you like detailed sound reproduction, not rolled off highs and bass like with the oldschool or modern classic SPU.
I've never tried #1e, but i think it's just the same as the Classic GM MKII E (budget model from the past).