If you have the means to buy Bitcoins i feel there are better ways to get into this money loop, specially the last few months with the recent capital repatriation tax amnesty.
The 6:1 exchange rate really only applies when you're a tourist going to pesos from dollars through a bank. You could also go to pesos from dollars at 10:1 on the black market. However, going the other way is really difficult -- to exchange at a lowly 6:1, you will need to have a receipt indicating that you purchased at 6:1 and to fill out some paperwork... and even then, there are no guarantees. With bitcoin, you'd run into the same problem since nobody will sell bitcoin at the implied government exchange rate.
For this to actually work as a money loop, you'd need to find someone willing to sell dollars at 6:1, which is unlikely since they would be losing money.