Just out of interest, was anyone DQ from the Badger Half for wearing headphones? I certainly saw a few on the route who thought that the rule didn't apply to them. Sometimes race results show any DQs but this one doesn't.
Brief your marshals well. Be clear about what they're expected to do for runners and what runners will expect from them and how much runners will (or will not) be aware of. They're the chaps out on the course, who could make or break a runner's race by directing them the right way or offering a tiny bit of much-needed encouragement at a crucial point. They need to be aware of what the course looks like from the runner's point of view so that they can direct them effectively. No-one imagines that marshals (and I include all volunteers in this) simply know what their role is, but the odd race I've been to recently seems to have left their volunteers to get on with dealing with runners' entries and queries with not much clue how to go about it or who to ask! Oh, and no marshal should ever say to runners "not much further to go!" ...unless there really ISN'T much further to go!!
I did it last year and the worst section of the course was the half-way point which was on a bridge across the river - the paths alongside the river had been fine up to then, but the bridge itself was a nightmare with tourists and football fans and the like. If having more of the race beside the river cures this then I'd be in favour of it!