Is PhantomJS still viable?

I am upgrading a front-end client written in coffee-script to latest libs and practices. We used PhantomJS to do some automated tests.

After upgrading to latest libraries I am having trouble making the code work inside of PhantomJS. It works fine in latest Chrome/FF but I am getting syntax and other errors in PhantomJS.

I have been forced to babelify my code, but still with little success. Is there a recommended/standard babel config for phantomJS?

Another issue seems to be I need to babel-ify also code from node_modules (which is slow and bad afaik) - for example we do some CoffeeScript compiling in the browser and the coffee script does not work when ran in PhantomJS.

Has PhantomJS gotten old? What are the alternatives? The only thing I found is slimmerJS, but that requires a separate install of FF. So I am at a loss.