i think that does help! easy to use? do the cartos/attys wear out? what best attys to use? who sells them?
They are incredibly easy to use. The life of the carto or atty depends on...well, the carto or atty and how you vape it. I do get longer life from my cartos with a bottom feeder as I don't "forget" to top off as I'm just pushing the bottle to get a fresh vape whenever the taste or vapor production prompts me to do so. I use Joye attys or the Vapage hybrid bottom feeder attys with mine too and they both work great.
I've tried/owned bottom feeders from a few places and the ones that Hogwart is making (search Hog's mods) are my very favorites and I use one of them daily. I have a variable voltage and a standard. Here's some shots:
The insides of the standard Hog:

http://www.flickr.com/photos/87267225@N00/5957503187/http://www.flickr.com/people/87267225@N00/
My VV and my standard:
