I'm using Linux but I won't consider installing a native application even if it were available, or if I had a Mac or Windows. Web apps proved to be good enough for issue tracking (maybe I'm telling this to the wrong people given your choice, which I respect), my browser is open all the time and it has offline capabilities. Furthermore, it can be updated more conveniently.

Another point is that issues are useful if shared. I shared links to issues to customers and coworkers countless times and included them in reports. A web client solves at least one problem, maybe two. First, they might not want to install (or pay for) another tool. Second, Ship references issues with the ship:// url, which won't work unless you have Ship installed. A https:// url would work for everybody but then you need to share two different URLs which would be cumbersome. I'm sure you already found a solution to that.

Your site doesn't address explicitly one fundamental aspect: the data are hosted on your server, like issues stored in GitHub, Jira, etc and you're selling the service, or will be. Is this correct? What's the pricing? Thanks.