Hey Lobes, yes I made a conscious decision not to use one, pretty much for the reason's that Goatman mentioned

At this time of year the rapids I paddle are fairly interspersed with much slower moving areas of water, so if I lose the board I can catch it pretty quick. I also never paddle moving water alone, so if I do lose the board my wife or whoever i'm with can paddle down and catch it pretty quick.
Having said that, I did come off earlier in the day and missed grabbing my board, and there was no way I was gonna be able to catch it until I came out of the rapid

In the long term when I have a bit more experience with my river in the lower water range, I will start wearing one in winter but NEVER a leg leash. Why would I risk wearing one in winter? My run in winter becomes very high volume, and if I came off I wouldn't have a hope of getting my board back. As it's high volume, the risk of entanglement is low, particularly since I'll be familiar with what is in the river under my feet as I'll have seen it at lower volume. Of course, the river changes all the time especially with logs etc but there is always a risk with this kind of sport.
Why not a leg rope? if you do get an entanglement or worse you may not be able to get down low enough against the pressure of the water to pull the quick release from your leg. I will be using a coiled leash (to keep it short, and out of the water) attached to a coast guard approved quick release chest belt such as are worn on rescue PFD's. This is what a lot of the river rats are wearing in the states, I'll see if I can put a pic up of it later and some links to a couple of posts.
I'm still thinking about it anyway, for me in the end it will be to do with river level, and whether the risk of losing my board and having to swim anywhere up to 10kms or so home outweighs the risk of entanglement