"It seems very promising, but I still have doubts until I had the opportunity to try it out, is there a trial version I can test?"
If you had the same doubt and want to give it a try, I think Brad's SEOLinkVine allows you to purchase credit for article submission! You can sign up a free account to get content while purchase some test credit for submission. Personally, I don't encourage per credit submission, you can only have some ideas about the system, but you won't really benefit from SEO standpoint.
Unless you join this service to mix up your links, I urge you to consider using the monthly subscription. You need to submit some volume of articles to make the result visible, and this system can be extremely powerful over time.
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