Getting feedback -- how many reviewers do you need?

Question

I'd like to draw on the experience of this group.
The Beta of our first training lesson is complete.  We did a careful internal review with a group of subject experts who offered detailed feedback. 
Next, we offered it to a variety of managers and their staffs -- the kind of people who would either take the training or send their staff to take it. 
Of that group (between 500-1K people), we had 32 people offer to review the lesson and send in comments of their own free will. 
However, of the 32, only five brave individuals have sent in feedback as of the deadline.  Life is busy, etc.
I know that in UX design and webpage design, you can get very good usability testing even with a small group.  A group of 5-10 representative people will catch almost all of the problems you are trying to find in testing.
What is your experience with reviewing Captivate training? 
In this case (unlike usability), we are not asking people to accomplish specific tasks, but to simply take the lesson and send their feedback on both style and content.
Is my small group of five (somewhat representative users) enough?  Or do I need to seek more?  And, in your professional opinion, how many more will catch what we need to change?
Thanks in advance!

Answer 1

My advice is to run with the sample reviews you currently have, make any changes that were highlighted as necessary, fix any bugs that came to light, and then get the course out in the wild as quickly as possible.
There's this perception in some manager's (and Captivate developer's) minds that you can't release the course "until it's perfect".  This is a mistake, because the course will never be perfect according to somebody, and you will never be able to get it released.
So waiting for everyone to be happy with your course will result in huge delays, by which time someone else will not be happy, or the business process will have changed, or the management team will have changed, or...you get the picture.
So cover off any glaring errors found in the review, and get it out there ASAP.  You can fix anything else that comes to light in 6 or 12 month's time when it's time to do the inevitable updates to content.  If there's some other showstopper that's "discovered" before then, do the change and publish an updated version.
These constant changes are what make using CD ROMs to deliver your course a bad proposition.  Totally online is the way to go.  You can put up an update overnite and nobody is the wiser.