Yes - in the right situation.

As long as you know your Dandie well and they have had basic obedience training there should be no problem But it is up to you to keep him safe. If, when he is off the lead, he (out of his natural friendliness) approaches an agressive dog who is on the lead - you would be putting your Dandie in legal danger because he would be deemed to have caused any fight/injuries that might ensue.

That sweet little obedient soul that lives with you might only have to see a sheep or a squirrel for example to run off for the chase and be quite difficult to retrieve until he decided it was time to return.

Dandies are quite happy walking with an extending lead although a short lead is recommended for walking near traffic or in a busy place.