Ok mate, from my experience, if they from good working stock, they make excellent ferreting dogs, as for concentration levels, the one i worked many years ago would have died on the spot concentrating, it was an excellent marker also.
As for lamping it was a 1 on short cut fields especially golf courses, but did struggle a bit on cropped fields.
Let him rag the odd fox, which had neared its end, but as for slipping him on a fox single handed
In my opinion they are to fine a dog to contemplate taking a hiding of a fox and you also need to be carefull where you lamp as they cant ta