Not saying your point isn't valid, I just want to say that when taken in context, Dash will not be confused with the LA bus that runs in circles at business centers like Downtown or Warner Center, The apple app that allows you to browse APIs when offline or the clothing detergent. All of these products and more have chosen the name Dash despite the frequent use of it because it is catchy, and fits their product.
Choosing Dash as the name for our product is going to work for us just as well, and it doesn't matter if other projects have similar names. Dash payment will not be mixed up with Dash the bus or detergent, they're just too different. Better still, the fact that when people hear the name "Dash", it will sound familiar, without knowing why. So when they learn of a new payment system, they'll get a feeling like it's been around a long time, and it will have instant familiarity.
So though it may not be a unique name, it actually benefits from familiarity, which, I think, will build inherent trust in the product. Also, I'm not sure if you aware that Dash holds the trademark for the name when used in the context of crypto currencies and the like.
What I'm proposing will happen above, won't happen until the general public gets involved in crypto payment systems 5 to 20 years from now (possibly as little as 3 years, but that's a very rosy outlook) Real marketers would have a better explanation of this effect, but I'm quite sure something like this happens when you get a catchy name like Dash.