The seller tells me that "Regarding the XLR connection, you can just re-terminate it to RCA, nothing complicated. The arm is the satisfy carbon direct-wire."
Most (all?) Clearaudio tonearms are direct-wired. The TT is being sold here:
http://cgi.audiogon.com/cgi-bin/cl.pl?anlgtabl&1328203877
So, no, the turntable does not offer RCA outputs.
I'm not sure what you mean by "cartridge output is inherently differential"; but if you are right that "[it] can benefit from a balanced connection but only if there is balanced input phono stage as well," then I would get better sound by buying a preamp with XLR inputs, but it would probably work well enough without one.
In any case, thanks, Kal.