question Are there any reasons NOT to activate Fast Transfer?

[elodo]

Any downsides, hidden dangers of it maybe - no?..

 

[Hypersot]

Fast transfer (I'm referring to Afternic's FT and Sedo's MLS) means that you give permission to a third party (ie. the sales venue) to remove and transfer the domain out of your registrar's account at any time without asking permission for that action.

If that is ok with you then, no, there is no downside.