there just aren't enough "proven" HH lines to make any kind of a blanket statement like that. other than the van leeuwen lines, i wouldn't give a pass on any HH line. however there are many xHH's that can do police work that come from various lines.
arko is just a PH1. again, no working police dog. BIG difference between this dog and the van leeuwen lines. typically, the van leeuwen lines produce VERY serious, VERY confident, VERY dominant dogs. dual purpose? maybe not. depends on the other half. i remember talking with dick about wibo. he said he cannot play ball with wibo because getting the ball back would a fight that he would just assume not have to deal with. doesn't mean he's not capable of it. for man work, and i mean man work, not sleeve work or suit work, the van leeuwen dogs are hard to match.
of course even within the van leeuwen lines there are differences:
wibo: ULTRA dominant, ULTRA confident, didn't seem to have a lot of play drive or any type of an off switch. no wasted energy or motions with this dog. not the snarling, growling, pulling at the line, barking his head off type dog. just stands there and eye-phucks you, knowing he can hurt you. very eery.
spike: more of a very good dog you'd see over here. seemed to be very high in prey, but the prey was directed toward the man and not equipment. lots of the high pitched barking, pulling, etc. the things commonly associated with a "high drive" dog.
robbie: kind of in between the above two. my favorite dog. tommy son (lots of those out there).
as for tracking.....i posted a video of a 10 week old tommy daughter tracking. pretty amazing. tommy is a pretty popular stud dog and there are lots of tommy sons and daughters, and probably grandsons/granddaughters by now. if you could get one of those type dogs, i'm sure it would do whatever you asked and you'd be pretty dang happy with it...