I'm thinking of purchasing a tacx trainer, but it's one of the lower end, older models.

Researching the trainer the product description says "Google Earth License Sold Separately". Am I right that if I purchase the google earth license I can build my own routes in Google Earth and ride them on the trainer?

I've read elsewhere that it's not necessarily the best as there can be random spikes/drops in elevations on the trainer due to inaccuracies in google earth, but I was thinking of importing route files from previous outdoor rides or importing routes from mapmyride. I'm assuming these "real rides" files are smoother, or does google earth alter the file on import which may result in the random elevation spikes?

Any experience/feedback using a tacx smart trainer with google earth would be much appreciated.