with terriers the urge to drop in is almost always there. and my best bushing dogs are the worst culprits. occupational hazard i say.
i used to be an obsessive earth hunter. and would travel hole to hole with terriers leashed. but now prefare to do a bit of everything with my terriers. i would probably be able to do well with spaniels or crossbreds, but i like terriers. so i take the rough with the smooth.
to answer the post i have one terrier that i find very usefull and does everything you say. but does drop in at every chance it gets.
and to be honest i wouldnt want it if it didn