
Having got an un-docked springer recently, I wouldn't have another undocked one.
We've never had a problem with our docked springer doing what springers do in gorse, but the un-docked one is constantly cutting the tip of her tail, the vet has given us an antiseptic cream to apply to her tail before and after walks to try and prevent infection, but I feel its only a matter of time before she gets an infection in her tail.
If you aren't going to walk your new springer in area's where they are going to be rooting round in undergrowth thrashing their tail from side to side as they go then fine, and when they're are happy, boy does that tail thrash, you can hear the tip thumping against her ribs.
Just my own experiance of owning an undocked springer, not an invitation to debate the fors and against of docking.