well, the VDR rules is one of the biggest reasons why i love astronomi-con so much. put simply, astro's 2 organisers allow VDR creations to be included in your army! of corse, you need to send in the info on it and they have the right to refuse your creation... (it's not a set of rules for creating insane & god-like killing machines after all!)
still, it's great that i can pull out my scratch-built 40k style blackhawk and have my armoured fist squad truck around in it instead of a chimera!
the main problem i saw when the local gw store allowed VDR creations was that you got perhaps 10 guys who did cool stuff that was great fun to play against with those rules, but sadly, you then had the 30+ arses who just plunked down something with as many guns as they could possibly glue to a dreadnought model...
cheers!