Here at R3 we extract data from customer's drives every day and we ensure that data is moved successfully without any issues. If there are any issues with copying then it's normally to do with the drive itself and not the actual software.
You can extract customer's data in a number of ways depending on the fault of the drive. If we are working with a drive that is slightly degraded, then it would be straight forward. In this case we would simply hook up the cloned drive to one of our copying machines and copy the data from one copying software program to an external drive for the customer to use.
In cases such as if the drive is degraded but also has a damaged Master file table, then we can't just copy the data there and then, we have to scan the drive so that the MFT has a chance of repairing itself. Then once the structure appears and the files are tested ok then we are free to extract the data.
With copying data that is HFS+ (MAC data), we can't just use the same copying software as we use for windows drives, we would have to use a different piece of software that is suitable for MAC drives and helps it to copy quicker.