I honestly don't think anyone can tell you whether it's worth you changing, putters are very much a matter of taste. The Ghost is a great putter, I've been using it since I reached L92 and love it. I had the L66 one before that and took to the new putter straight away. I tried the Nike but couldn't get on with it, particularly the 10 foot scale which just seemed dead. I suppose if I'd stuck with it I could have got used to it but I was playing well with the Ghost so figured why have a dozen or so bad rounds while I adapted to a new putter.
I can tell you the Ghost is a good putter if you hit the ding, less so if you miss it, intentionally or not. There are many here who aim putts by missing the ding rather than moving the aim marker and the Ghost won't be a good choice if you do this. It loses a lot of distance if you do and becomes hard to judge. I aim to hit the ding almost every putt and get on great with it although I know missed dings probably cost me a shot or two per round.
Shame we just had a free rental weekend, that would have been the ideal chance to try it out over a couple of days without having to pay.