I just was able to directly compare two different tonearms again, and, again, I am impressed by the difference a tonearm can make! This time I was able to compare a Schroder CB and a Kuzma 4 point on the same turntable with the same cartridge, and the sonic results are as if I had changed out a major component, such as a pre-amplifier, or amplifier. (As a reminder, I started this thread by noticing such a similar dramatic change in sound quality when comparing a Schroder CB tonearm with a Reed 5A tonearm.)
The Schroder CB is an excellent tonearm, but at at half the price of the tonearms that I replaced it with, it perhaps isn't an even comparison: apparent differences in detail, clarity, and sound stage are most marked.
In my estimation, the tonearm may have more of an impact on sound quality than the cartridge used.