Hey,
I'm in my second month with Ad Drive. It seems like they're the ones who are buying the ZIP submits because they can quickly tell how well your campaigns are doing. This can be a very good or very bad thing depending on how you approach it.
If you are driving PPC clicks to it that are targeting a relevant audience, you should get plenty of submissions. More importantly, if the submissions that you sending are converting well for them on the backend they WILL boost your per lead rate.
Now, if you are doing any form of black hat / iframing this might not go so well. Since they can quickly see how it's converting on the backend they will know right away that something fishy is going on.
Very solid company from my experience with them thus far and I'd highly reccomend it. Support is very good too.