I recently played a friend's early '30's Conn alto - it had no resos. Nice, sweet sound. The trumpet player sitting next to me commented that the Conn lacked some of the edge that was present in my Big B alto (with snap-ins). That was my impression too, but both altos had nice tone and I'm not prepared to claim that the presence or absence of resos made a difference.
I am not convinced that resonators make a difference, either by their designs (plastic vs. metal, NOYEKS vs. domed non-rivetted, snap-ins vs. whatever, etc., etc.). I don't think a one-horn comparison, especially after a tear-down and re-pad is a valid test of the premise, either.
There could be several reasons why the horn sounded different after the re-pad. Like so many things saxophone, there are many myths floating about. To prove the issue, one would need to play, tear down, re-pad, re-assemble, play again . . . and do it over and over with a whole bunch of saxophones before reaching any conclusions about resos, lacquer (or absence thereof), plating, and other beliefs.
However, I admit to having a Yanagisawa soprano recently done and I opted for black Roo pads with smooth domed chromed resos (non-rivetted that pretty much filled the tone holes). It plays great but I honestly believe it was the way the horn was reassembled and not the resos. The response improved but as far as the tone goes, it always sounded good. DAVE