Its a neat idea...and obviuosuly some thought went into it but...
1) its more stuff to worry about
2) if you are running 1 1/2 or 2" pipe, the wires can bind against the inside of the pipe (never seen it happen on mine, but others have .. sorry couldn't find references for that ) ...a slip ring at the base may mitigate that somewhat..... guess it depends on the tower height and the wire.
3) depending on the height , and the forces needed to swivel the the slip ring , may not do as you think. If its easier for the wire to twist than move the slip ring, slack in wire.. hmm ?
4) See #1
If it works for you,.. cool.. maybe it will answer someone elses issue. I prefer the KISS approach.