I would prefer single-ended, sonically, myself. But at 17m I think balanced is highly advisable.
Actually, a very good experiment would be to get Mogami balanced and Mogami single-ended and assemble a panel of WBF members to compare the wires. (I will provide snacks and alcohol.)
Ok, but you would still be comparing Mogami to Mogami, question is whether these results would translate to other..shall we say..more accurate and resolving cables.
Years ago,I owned a cable called Highwire, for its time I thought it was unbeatable. The designer ( Don Palmer) had included an online RFI device as part of the cable that allowed for long runs with no possibility of RFI interference. Wonder why others don't seem to do the same thing today.