SPU: Original mono vs modern mono cartridges

I see that Ortofon SPU CG cartridges are original (or true?) mono cartridges in that it only moves laterally, while more modern SPU Mono cartridges operate differently.
Has any of you have experience on those two cartridges?
When you play 50's mono album, do you hear any difference?
One of my audio friends suggested me to try Ortofon Mono CG 25 Di MkII rather than SPU Mono GM MKII, and has tried to convinced me that the sound is very different, and those 50's mono albums would sound real nice with CG 25.
Any input?