The main thing you will notice is the full richer sound of the Wersi voices demonstrated compared to the more flatter less involving T4 sounds, as to which is the best has little relevance, as some will like one whereas other will prefer the other.
I suppose you're right, Bill...some will like one whereas others will prefer the other. Sounds are very personal and highly subjective.
To my ears the Tyros4 has a much more impressive and detailed sound, even without any extra packs and it's instrument emulations (especially SA/SA2) are second to none, in my opinion, of course....I'm aware the Wersi has more appeal to you, and it sounds pretty darn good, however it doesn't seem to be an instrument I'd like to live with, and listen to, every day. Basically, the overall sound is dated...good, but dated.
Of course, that's why I use a Tyros4, and you don't.

Perhaps, if we had a dealer within a reasonable distance, and I could actually spend some quality time with the instruments (I come from an organ background)I may grow to like the Wersi sound more than I do at present.
It's great to have choices and it's nice to see that we've both found what we wanted.
Ian