Recently switched to primarily Euro-nymphing and more recently switched to mono-rig style and bought TacticalFlyFisher's euro nymphing leader and thoroughly enjoy it. The leader is excellent - I had it in my primary setup for a few months and now setting up my backup outfit with the same leader as well. The only thing that I miss from my old RIO euro-nymph leader is the opaque butt section above the sighters - I found that to be more visible than the chameleon in this setup.
Perfect Leader - Thinner
I purchased a thin model earlier this year after I received Devin's book. As described it was sagging quite a bit with smaller flies while using an up and across approach and dry-dropper fishing. I recently purchased the thinner model, and the sag is nearly eliminated while fishing both methods. The thinner model is now my preferred leader with almost all my trout wade fishing, using a 10'6" 3 wt while dry-dropper and tight-line nymph presentations. Can't recommend it enough, stiff enough to turn over bushy dries and supple enough to accurately present nymphs and detect strikes.