Is there an exit fee for joining or leaving Shape Shifters?

No, there are no exit fees for Shape Shifters. 

This is the case for both versions of Shape Shifters - Trio and Agile.

You don’t have to pay an exit fee to move from your current Octopus contract to Shape Shifters. If you’re partway through a fixed contract, don’t worry. You can leave that and switch to Shape Shifters at any time.

There’s also no exit fee for leaving. So if you join and don’t like it, you can switch to a different tariff - including the other version of Shape Shifters.