Since buying a couple of merino tops a few months back I am completely sold on the stuff. For years I had been using Helly Hanson Lifa or Sub Zero Factor 1 thermals. All of which developed that characteristic kayaking odor.
My current kayak thermal of choice is the Howies merino surf thermal. The merino is thin, the arms are nice and long and also include thumb loops. These are superb when your putting on your drycag or dry suit as they help prevent the sleeves rolling up. The neck is a turle neck so you get a bit of protection from latex dry cag seals. I managed to pick up two of these thermals before they stopped producing them, one of which was found new on ebay. They do come up now and again. The NBL or NBL Light are probably the closest match and are in the current range (I own a couple of these as well).
Although most merino tops are relatively expensive compared to synthetic thermals they do offer a number of advantages. The fibres of the merino wool are different to both synthetic and regular wool, this makes them softer, non-itchy and resistant to the stink monster. The lack of that kayaking smell is one of the most obvious advantages, but they also offer a good level of warmth even when wet and they provide a good level of UV protection.
Cheap Merino kit often appears on Sportpursuit at regular intervals.