Anyone running Propane, or thinking about it?

I have been reading on www.gotpropane.com and was wondering if anyone has done a conversion to propane. They have kits that cover up to 420HP. I now Schwan's runs propane on all their trucks, but I was curious about personal use.
Their website has a lot of positive info, but of course no negatives. Here is what they are saying:
Propane
Will not go bad
Burns clean
Requires no maintenance
Is easy to install
Is very safe
In many cases it is much cheaper than gasoline
Rates at 100-110 octane
Automatically compensates for altitude
Prolongs engine life
Is affordable
No loss of power with any of our kits (these are automotive kits)
No wiring except the on/off solenoid.

All of our kits are complete with all the parts necessary to do the conversion. They do NOT include the tank.
All of our kits are designed to be installed to NFPA 58 standards.
Propane is not harmful to soil or water