I'd reckon, the gravel will dissipate most heat that misses it's
target. Only problem might be the odd stone splintering. This is only
if you aren't a very good aim. The flame gives a nice blue cone so
pretty easy to direct.

I think, that you don't actually have to fry them to a crisp just a
light toasting. Presumably the heat destroys the cells structure
enough. That being said it's not as satifying as watching them keel
over in flames.

My thinking would be that I'm still using chemicals anyway (well
burning them, but it still damages the environment if you want to be
that picky) So I just use whatever is most effective.

I believe glyphosphate breaks down very quickly when it reaches the
soil but some of the regulars will probably be able to confirm/refute
this.

Other things I forgot to mention. I'm about 6'1" and it's about three
inches too short for me. Just perfect for that stoop that causes a sore
back. I'll need to get longer arms. Oh and it makes a pleasant pop
sound as the last remnants of gas burn after the valve is closed
Well it amuses me...

Mark.