I like that they have both an audio version as well but also in text form which is very useful when you are trying not only for your own benefit (to learn)but more so because it's great if there isn't anyone around who can read out loud! Sometimes we need this type ot thing especially at work where sometimes no one else will be available or even willing too do some reading/writing duties - plus its easier than having someone come into my office just once every week etc..
There really aren;t any downsides other then maybe how quickly time goes by with them being such busy people? If needed i would say try working together first before deciding whether something needs replacing though personally id rather get feedback from others about what works best instead!!