Some feedback. I think that the idea of the cache that can be found by only one person, is right one to add "insider clicks". Even without them, there's cases where some cachers make "insider-caches" ( usually some D4 unknown cache ), and archive it immeadiately after some unknown or not a friend-cacher finds those caches. So this whole idea just seems "official" blessing to this kind of behaviour, and even gifting these insiders their own cache type!
What I like in geocaching, that everybody have an equal change to find every cache in the limits of their own physics and wits. Cachers are usually quite friendly towards each others, and even some are competitive, competition is "pure", except for the above mentioned cases. Since amount of the found labcaches is listed ( maybe even in statistics some day? ), there is always possiblity to do some doping with this cache type: -If I make 20 labcaches for you, would you do same for me, so we both have more than cacher X?
So in short, I don't like this new type of cache.