I get what you are doing, but comparing systems on good quality LP's using a low quality cartridge is the wrong way to do things. If you fit a much better cartridge you will find your observations different as you will be properly evaluating the system.
However a good cartridge also needs a good phonostage, and none that you have listed are Hi Fi quality. This is a great project, but it would be a great shame to make less than good archives from them ?
I analysed the files on WaveLab and also a RTW analyser and played them back on a $50K+ Hi Fi system. The first track "Am I Blue" would so benefit from a mono cartridge or a true "mono sum", you would be amazed (note this is not just a simple mono/stereo switch). The rest were good but so-so. Your request "We are seeking community feedback to help us find the best sounding recording chain." could be fulfilled right away by using a quality cartridge or two and a good Hi Fi phonostage. Without those everything will sound similar. This is a worthy project that deserves worthy equipment and careful archiving.
Member of the ARSC Technical Committee