We have a bunch of propane converted small engines at work(pretty much anything 4 stroke, and gasoline fueled)....
Never have any problems with them, and the oil doesnt get all black like a regular gas engine...
ANYWAY, I think for OUR intended purpose remote camping, etc... you really cant beat it... the fuel wont spill, if done right, can be stored on vehicle safely(maybe even an RV tank mounted underneath depending on your app?) AND, you can power the gen, ck stove, lanterns, grill, whatever off one fuel.... In my case w/ a diesel truck, it makes complete sense...
For, I dont know.... but, I have to say, I like the way the small engines start and run on the LP...
Chase