I haven't used the tadpoles, did see them being used on a show last weekend...
Mark Romanack's Fishing 411 (not sure if spelled correctly)
The episode may be available online for viewing
this looks like a very similar system to a weighted diver that we do use in the Chesapeake bay, they are simple and easy to use.
What I didn't see on the episode, is what depths they achieve, though I would think they should have more info available on that from a manufacturers website.
Treefarmer, if you do get them, post a review... I'd be interested to see how they do for you.