I think something our field may benefit from is a guide that explains how to use the different usability services and at what point in the project cycle they should be used.
Another hack to is to do testing in student centers (as opposed to bars) so you can get people on their own computers.
http://news.ycombinator.com/item?id=785489
http://www.i-proving.ca/space/David+Jones/blog/2010-01-27_1?...
Then again, Feedback Army is just a usability testing tool. The right one for the job. I think it's best when a breadth of ideas are needed quickly or you need some ideas about where to start improving your site.
You should use other methods to do testing that requires a lot of depth from one or two people.
Here are a few more posts where folks have written up their experiences:
http://visualwebsiteoptimizer.com/split-testing-blog/how-an-...
http://www.mattmazur.com/2010/02/reflections-on-precedens-ha...
(p.s. I run Feedback Army :))