Anyone here have any experience using something called a Lawn Vac?

Here's an example:

http://doitbest.com/Power+rake+and+t...sku-717282.dib

In case that link is too long, try this:

http://tinyurl.com/d6fp6p

These things all have the same basic design. They sort of look like a
lawn mower, except with a wide intake attachment up front (and optional
hand-held hose attachment). They pulverize the intake material and
shoot it into the bag.

I'm wondering if they're a lot like lawn mower with a closed bottom end,
and something that looks like a mower blade is doing the vacuuming and
pulverizing.

What I'm wondering is if these things are good at pulling small gravel
and sand out of the lawn that's close to the road (sand and gravel put
down on the roads by the city during the winter).

I've also come across something like a weed trimmer with an attachment
that looks like paddles.

And one that looks like a rotating bristle brush or shoe cleaner:

http://files.kooybros.com/Echo%20PB270B.JPG