I dont think it would be much more dangerous than an LSD. Just more responsive as the axles are locked into each other permanently, and it doesnt have any give when you go around corners. your rear tyres will squeal going around a round about slowly.
on the street it will tear stuff up- a friend of mine had a jeep with a locked up rear posi unit- when turning corners it didnt just 'squeal the tires', it would kinda chirp,chirp,chirp, violently, tugging at the steering as it turned corners...large tires probably aggravated it...would think twice about it on the street...in the wet you could spin out very easily.
limited slip can have similar problems, but not nearly as bad. I remember years back, hotrod had an article on "$1.98 posi"...i think they just shimmed spiders a bit snug in 9" ford, got carrier drag similar to that of limited slip. I'll see if I can find the article...
One of the muscle magazines back then ran a tech article on how to convert your 9" open rear to a posi type locking unit for only $1.98.
The short story is: Buy a new pair of Ford 9" Side Gear shims from your Ford parts counter and install them IN ADDITION to the pair already in there. That's it. Put it back together, add gear oil, and go racing.
The Side Gear Shims are the gears that your axles pass thru on each side. By adding the extra pair of shims to them you pre-load assembly into a sort of limited slip.
The article went on to say that who knows how long it will last, but hey, for $1.98 what do you expect!?
I've tried this on two different 9" rears and yes, it does work. I exploded the 1st one after a couple of hard years, the other one still sits under the car in one piece. As a little admission of guilt, I added the shims to the 2nd 9" rear because it wasn't locking up very well. It's a Traction-Lok unit. May the God's forgive me!
The above was only thing I could find on that article, but he explained it pretty much...
Spools are illigal on the street for a reason, and the first cop with half a clue that sees you 'skipping' around a corner will have your ass. And don't even bother trying to park it, especially if its manual and you don't have power steering.
LSD's are tough enough for most purposes. For street driving the only other choice is a detriot locker, but thats a serious upgrade worth a few grand.