If you used the heart rate monitor to pace yourself, it would motivate you to go out too hard -- an even better reason not to pay attention to heart rate monitors during races.
IIRC (and unless I`m mistaken) the wizard simply calculates 81% of (given or estimated) heart rate reserve and gives that as the suggested race HR.
As far as a ballpark figure for a reasonably well-trained and -rounded runner goes, I find it quite OK, but it could indeed be too high for someone whose lactate threshold or, more to the point but perhaps even harder to define, marathon threshold is lower than what the wizard assumes to be.
Using a HRM in a race is great. You don't have to use it for your primary pacing tool, but it will help you in longer races keep your effort at the % of LT that you want. Also, even in shorter races when you can get swept up running too fast with others it can tell you to back off a little. I've never found that I pay TOO much attention to the thing in races. And for post-race analysis it really is great, especially if you have a computer link, and you have a lap function for splits etc.
