I have a small perc bong which I used a few times for Changa. I found that my usual 20-30mg (40-60mg changa) doses really didn't 'hit the spot' like they were in a standard bong, so I stopped using it as a spiceship. I came too the conclusion that the extra water filtration was detracting from the experience somehow, maybe by re-condensing the vapor / smoke. Now I either (very very occasionally) use a standard bong or more likely my GVG. What I think makes the GVG a great device is that it produces smooth vapor with no need for water, meaning that there is no likely-hood of the spice condensing, or of spilling bong water on the floor once you lose motor control, plus there is less cool glass tubing for it to condense on along the way...

These health stones do look very funky though, if I had access to some hash oils / waxes I would certainly be keen to test them out.

Just for Mr. Cyantifics reference - I generally break through at just over 20 mg, over 30mg and it becomes super intense and difficult to remember. Most of my doses are 25mg like Mr. Tele.

Peaz