i guess it depends on your location but is a smoker escentual?
in some places yes,i dont go ratting with ferrets so if it cant be dug out fairly quickly ill use a smoker.the rats in one big tree trunk wouldnt have moved without it.you could have maybe smashed it up but i dont think the keeper would be very happy.then theres the times when rats are in tree roots,old stone walls,under concrete floors etc etc etc.
even if i did use ferrets i wouldnt put them into some places,same as you wouldnt risk a terrier in some earths.
having said that most of my daytime rats are taken by eit