Judging from my own affiliate statistics I would say that staying 10 months was about 9.25 months more then other people so I think I had a pretty good handle on the system.
Now that I have no affiliation with the product I can more convincingly say to you that the product does work...when used correctly. The problem I saw with other people using and inevitably leaving LinkVana was that they didn't understand how search engines work or how to properly leverage the tools in front of them.
The easiest way I found to put LinkVana to good use, was by promoting user generated content sites the search engines already like. I would dig up low competition keywords, write and post an ezine article, then use LinkVana to bolster it up and I would be off to the races. I could do this with other article directories, squidoo pages, blogger, youtube etc. They already seem to have a leg up with the search engines and combined with LinkVana the results were really great in terms of rankings.
I typically went after 50+ searches a day < 50,000 competing pages and targeted the social sites that were missing from the first page. (Ezine, squidoo, youtube)
After a couple of months promoting with LinkVana I would have winning campaigns with the search engines and start to make some affiliate commissions.
Why People Fail
The people I saw using LinkVana (and who quickly left) were using it poorly for one of two reasons in my opinion.
1) They were going after ridiculously high volume and competition keywords like '**** Berry' or 'weight loss'. They didn't stand a chance and after three whole weeks of posting with no sign of their site moving past page 1000 they would leave. First off, I usually didn't see rankings moves for 5+ weeks on relatvely easy phrases. And regrettably, Google isn't willing to give you a big hug and kiss when a new site gets a couple dozen new links for those hyper competitive words.
2) The second reason for inevitable failure was because of operator deficincies in keyword research. They went after really long and out of place keyword phrases like, "I want to cook spaghetti with my eyes closed". LinkVana did its job but it can't turn coal into a diamond because being number one for a phrase with no searches is like coming first at whistling shows...nobody cares.
Why I left:
You are probably wondering why I would leave when I could sit there and build these somewhat profitably campaigns all day long. Well I moved on. I honestly got tired of kicking around for these low search keywords that would inevitably make me a couple sales every month but not what I wanted for the effort put in. Secondly, I had a mind set change with how I felt SEO should work. I decided to stop 'gaming' the search engines in favor of simply creating good quality content/products on my own sites and allow the search engines to do what they do best.
Another reason was the way people use search engines. I have heard stats that as much as 40% of all searches are unique. My sites were getting hits from so many non typical searches spending the time and dollars to go after the select phrases in LinkVana lost their return and appeal. And finally, PPC for quick targeted traffic is just so much easier then SEO. I can test larger and bigger offers much more quickly.
So to those wondering, yes LinkVana works. It does however take a few months for you to see results so be prepared to put down 450+ and time writing. You have to be realistic, it is not a magic bullet and it is not going to be right for everyone.