After climbing with a basic passive-rack all summer in J-tree, I looked forward to having the options of a hex with the weight of a nut. I think the tri-nut is a great idea in theory.
In practice, it failed to perform as a nut. I purchased 2 different medium size tri-nuts to compliment my most commonly used placements (basically a #8 and #9) nut. I climbed 4 different easy routes I am comfortable on that take passive gear well: White-lightning, Frosty Cone, Mr. Misty Kiss and Men with cows heads. Both tri-nuts were placed on each climb at the best nut placement for a typical huervo or WC rock with a 24" trad runner. I then set the tr-nuts with a full strength jerk. On 5 of the 8 placements, the tri-nut simply pulled out as I climbed past it from 'minimal' upward rope pull. In my opinion they either have too little surface area in contact to "seat" properly or the metal used should be softer for a better hold in granite. They still work well in opposable placements which accounts for the other 3 of 8. Maybe they have a place in aid climbing as they will be easy to clean.

These things are pretty darn cool. I was skeptical at the claim of being able to fit 3 different sized cracks. I was expecting maybe a mm or less between crack sizes on one nut. But NO! The difference doens't seem like much, but it is plenty to jsut rotate the nut and get that perfect placement, instead of settling for jsut making it stick. The mono cables on the smaller sizes are nice for squeezing it into a tight crack, and the teardrop insets on the sides are great for fitting it in solid. The only thing I would worry about is that some of the thin sides on them (each position has a wide side and a thin side opposite it) may put alot of force on softer rock, crystals, or imperfect placements. As usual, proper care should avoid a less than safe placement.