I agree with all the reasons NOT to. We tried for some time to use what's out there, and wound up writing our own anyway. Why? Mainly because most of them are too cumbersome to engage anyone but the technical people. We even tried basecamp (which, of course, isn't designed for this and failed in that regard).
We also came up with some unique functionality that worked great with our clients: a "report a bug" button that we scripted into code with one line of javascript. It allows our clients to open a small window, jot info in quickly and submit to the database.
But, it certainly took many hours to code; became a BIG pet project; lots of weekend time.
If you want to check it out: http://www.archerfishonline.com
Would love some feedback.
