Gentleman,
Over a year and 1/2 ago I looked into both the Halcyonics and Minus-K isolators. One designed with bells and whistles, { translation; what will it cost if something goes awry?}, and a somewhat low weight capacity, the other designed on sound physical principles, passive and a weight capacity I needed- 750 lbs.
The people at Minus spent more than enough time to educate me in the operation and application of their unit. It took a special unit to isolate the 750 lb load I required. The cost upgrade was much lower than I expected, and after taking delivery of the isolator I was impressed beyond my expectations!
Ivor Tiffenbrum of Linn said, " If you haven't heard it, you have no opinion." I never heard the Halcyonics or my Minus K. The Minus K should be performing by Christmas, so I'll have an opinion on it then; but I guess that on this thread it won't really matter, it's just another expensive opinion to a real world question.
*****If you look at the Mapleshade web site you will see racks built on sound vibration isolation principles that don't cost a fortune, gee they look like--- but are much cheaper! Money back gaurantee. The only Mapleshade products I own are a load of their Jazz cds.
Ken