Well the problems are not insurmountable, obviously, but someone will have to invest the time/energy/money to sort it all out for the DIY crowd and identify all the risks along the way (and not kill anyone in the process). All that is intimidating enough to be a non-starter for a lot of people, don't you think? Especially with 500 psi adsorption already being road tested in numbers?
Energtek Completes Lengthy Urban Field Trial of CNG Lite(TM) - Bloomberg
If I knew some more details about it I might put one on my scooter.