I have been using a Zav for the past couple of seasons and I don't see myself going back to wood.  That being said, there are things that the Zav doesn't do nearly as well as a nicely crafted wooden long bladed paddle (like a beaver or otter tail.)  If you like keeping your blade in the water throughout without ever having it break the water then the short, wide blade of a Zav is not nearly as easy or pleasant to use.  But for long and especially windy days, it is the best and makes my other paddles feel like 2 x 4's.  I also like the Zav in the shallows.  I have some long-time tripping friends who definitely don't share my zeal for the Zav but the bottom line for me - my lightest wooden paddle is about 20 oz.  My Zav is 8.5 oz.  Multiply the difference over 8 hours and then multiply that by 22 days and my shoulders say "Thank you."