As a hazmat guy, I have no problem using propane on my gas barbeque.
What ruined my weber bbq experience was learning that those flavors you are referring to are also chalked full of unburned radicals and other nasties through the smoldering effect of the contained fire. You want that smoke but it's the stuff in the smoke that we as firefighters worry about in regard to inhalation / cancer concerns. The only difference is that you are ingesting it. We know better. This is more of a big deal for young children (small biological units with multi-dividing cells that sometimes also have opinions.
But still... damn it... the meat tastes better using oak in my opinion but I rationalize that it is ok as long as it is an open fire... Will you back me on this one Karr? Anyone?
"Happy cows make happy meat, the kind of meat that you like to eat!"
On a personal note, I like the smoky taste for anything slow barbecued (like ribs or shoulder meat - neither of which they know how to do in do in Australia) but I like the high heat of gas for fast cooking steaks and pork chops.