We have been a long-time customer and we are very happy with Ezine Director's performance.
I have used quite a few different services of your kind, and I think yours provides the most value for the money of any I've seen. Great tool!
I think this is an excellent way to acquire paying customers AND will give many potential users the option to see if they can build a decent subscribership without having to front the $250 or more that would be needed for ListBuilder.