A money-back guarantee isn't compelling for me, for several reasons. First, I know that I would feel guilty asking for money back, and I want to avoid being in that situation. Second, I don't fully trust money-back guarantees. Third, that's ~$100 that I need to part with when I might see within 1 hour that the product is not a fit.
A free trial would be far more compelling.
FYI I'd be using this on Android.