Hi Raul,
I read Ralph's comment about the equivalency of the Tri-Planar and the Graham Phantom in the context each arm running with a compatible cartridge. Nothing new here for us (grin).
Of course, since Ralph's main experience is with the Tri-Planar, he shared his experiences of cartridges that have worked for him with it.
I would add to this Tri-Planar compatibility list, the Dynavector XV-1s, the Benz Ebony LP (the original - I have not tried the newer incarnations), and yes ... as surprising as it sounds the Denon DL 103R (albeit a bit lower on the sonic food chain).
Indeed, the Tri-Planar and Graham Phantom are different architectures. I have not played with the Phantom, but I wouldn't be surprised that with a compatible cartridge that the two arms would be more alike than different.
In my experience (I'm repeating myself from other posts), competent designs from designers who know what music sounds like, applying differing architectures, sound more alike than different. Yes, each architecture will reveal its distinguishing characteristics, but the designs will be shockingly alike.
Why? Because good designers know what real music sounds like.
The more pieces of good gear I discover, the more I learn later that the designer is not only a solid technician, but that (s)he has at least played a musical instrument - perhaps not mastered it, but played one. Of course, there are exceptions.
Cheers,
Thom @ Galibier