I’ve written a “Papers to Bookends” export script which should help trying out Bookends when you’re coming from Papers. While that’s probably too late for you, Craig, I’m mentioning it again in the hope that other people looking to move from Papers to Bookends may find this helpful:
Bookends is robust, and has indeed world-class support. Plus, as mentioned in the above linked thread, Bookends features extensive scripting support which opens up great opportunities for integration with other apps, and further helps to avoid any kind of lock-in…
So, IMO Bookends is definitely worth trying out. I’m also using Nisus Writer Pro and I can recommend it as well.