They sure designed the top of that front rack awkwardly, as well (with rails that stick up). You can't put something flat across it.

The Surly Nice Rack is... nice for all the crazy attachment points, but the Jandd Extreme is much cheaper and plenty capable/durable.

Edit: I know your looking for something light, but larger front racks solve just about every problem you might have with smaller racks (durability, size/weight allowance) at the cost of some weight.