Looking at picking up a 2-pack Cardo Scalarider Smartpack comms system. Cardo claims 1 mile range on bluetooth and 3 miles on DMC ("dynamic meshwork communication"). No doubt this is under ideal conditions - flat terrain, no obstructions, no interference. Does anyone have any real world experience as to what the usable range actually is? Also does the DMC only work for a large group or are just 2 riders able to use it for the longer range (compared to bluetooth channels)?