I think I read a few posts on both networks which stated both were poor quality sites, particulary for the price and distribution (Linkvana 1 article 1 site, and Linkvine 1 article goes to approx 3-5 sites at most)... And usually, these sites were deindexed after a period of time too.
I'm not entirely sure, but I also read that one of these networks had many sites sharing IP addresses (say 10 sites to 1 IP or something along those lines).
The services may of improved, however I don't use them. I last tested Linkvine 8 months ago, I put in 3 well written and hand spun articles, and after 3 months got a total of 7 articles distributed.