I don't have personal experience but have read some from vets
2iu is a low dose good for feeling younger, helping recovery, a little leaning out over time, and maintaining muscle mass when dieting
4iu is a dose that is better for fat loss
10iu is a dose for mass gain
The advice from most guys is that you need to take it for long periods (6+ months to really see the effects) and it is not as effective at burning fat as say ECA or Clenbuterol.
Hope this helps.