I almost agree with OxKing here! It does appear a bit one-dimensional to balance security against profitability. Ideally a site would be really attractive at first, spark some sort of lawless gold-rush condition. Then a major faction would move in and take control, upping security until the easy bits have been mined out. Otherwise a site may have some level of prospectivity, with only very occassional sweet spots. The major factions would likely appreciate receiving a steady stream of metals and minerals from those, but not really spend much effort on patrolling the sites. Someone could strike gold, so to speak, in a low-prospective site (turning it highly prospective) and the gold rush would start again leading to the first situation.
In both cases, the low-high risk situation develops from one to the other.
The system now is static, it seems, and mature - that is, the security vs mining profit has already balanced out.
A bit more dynamics on the fringes would be great: A "free" economy would have minimal profit margins in the busiest central regions, but large profits to be made on the periphery although possibly at smaller quantities of goods. Rare goods should stay rare, or they wouldn't be eventually, as the market gets saturated.