Canon WFT-E3A - max range?

[RobC]

Hi

I'm working on an idea that involves using a Canon 40d with the WFT-E3A wireless unit.
Canon specs claim it's useful wireless range is 500' (much further than earlier models).

I'll be using it outdoors in a line of sight setup.
Has anyone tried one of these?
Does it really work up to 500'?

Thanks
Rob