No experience with e-form, but since it's formestane it should ONLY be used on cycle as an anti-estrogen. Some people will tell you it's OK for post cycle, but since it's mildly anabolic I think it's defeating the purpose.
6-oxo is typically used post cycle. Most people on here will tell you that you're throwing money away if you use 6-oxo because research chemicals such as nolva and clomid are much better.
~Todd