I recently finished work on a Hayman Vibrasonic gold ingot kit. I put down some thoughts about Hayman in my non-commercial gear blog. A lot has been said on this forum about Hayman, but in my post I tried to collect the issues and idiosyncrasies in one article. Looking forward to any reactions.
http://maturedrummer.blogspot.com/2013/07/thoughts-on-hayman-vibrasonic.html