Docking of tails is legal so long as it is a vet that carries out the procedure. And yes, Springers can be shown undocked, the breed standard now includes this with regards to tails:
Tail
Customarily docked.
Docked: Set low, never carried above level of back. Well feathered with lively action.
Undocked: Set low, never carried above level of back. Well feathered with lively action. In balance with the rest of the dog.
I think they look great with tails! And why would you think he looks like a cross just because he has a tail?! It takes a while to get used to seeing them with long tails-I have 2 docked, 2 undocked but I think they look great with them and given the choice I would rather have all 4 undocked! :)