I own and use the SP10 MkII, in the form of a modified version, in my own system, as the preferred TT, over other owned TT's available such as DD's, Idler Drive and Belt Drive.
Additionally, I am regularly able to receive demo's of other SP10 MkII's in other environments, as well as a SP10R.
What I have learnt from this is that I am quite stimulated by the presentation of the SP10 MkII's and R, the enjoyment factor is present for myself when a Tonearm or Cart' is in use that differs from my own selection. At no time I have been presented with a presentation that has been repelled and not wanted to be continued.
The nitty gritty of design and spec' differences between the former and later models in use, is not something I have got too bogged down in, even though I have been on a few occasions in lengthy discussions about the merits of these variants of design.
As my own is a Bespoke Tweak Model SP10 MkII, and I know how the original and later models show differences in their design and function.
From my standpoint, the stimulus on offer from a performance is what really matters, and from all Versions encountered, there is stimulus aplenty, enough to keep other available TT's in their storage boxes or as dust collectors on shelves.