elchebib
Yes, they do have a fair usage policy to prevent abuse.
How much you need to reach this policy is hard to answer. But I can tell you that I did reach approximately 14 GB one month and it didn't affect my internet speed, so its safe to say that you can downlaod 14 GB without any problems (its not something for sure, it may depends on which central you're hooked to, how many months you exceeded their "policy limit" and so forth; no one can tell for sure).
My experience with IDM is great and have yet to face any problems.
However, if you're planning to play games online, be sure to check your NAT type because it greatly affects your online play. In addition, their ping times are high and the ISP that has the lowest ping times is Ogero.
