Let me also share some of my experience with btcflex
I did not invested even 1 satoshi into it
initially when they started they were paying for advertising them so I wrote an article for them and posted in my blog for which they paid me 0.05 btc
with this I had earned around 0.08xxx btc and had withdrawn all before time and got all money in my wallet, do note that all my withdrawals were around 0.01 or less each time but since the last few days I see the domain is not available any more and the site does not open so like all ponzi this has gone over it
my calculations were right I started with them when they had only 5k ppl, I knew by the time they reach 50k + ppl they would shut down and run away so i took out whatever i could within time.
this was my first time ever with a ponzi or hyip scheme and i hope am at the winning end
this was the article i posted for them:
http://fr33bitcoin.weebly.com/blog/invest-in-bitcoins