The link I posted previously....similar to this:
https://www.gunneboindustries.com/PageFiles/16842/Web - Picture.jpg
Besides the force causing it to close tighter it has a lever that locks it closed so that it can not open by itself. Closed system before all the aluminum expensive bling.
AAA trained and certified recovery specialist in a previous life.
So this one then...
I'll have to go on record as disagreeing with you here. The hook you speak of is common in the overhead rigging industry (we used to use that same hook for helicopter logging but that's another story), it is very strong but it is
not a "closed system" as you can see above - that gate opens up.
Anytime a hook is used, there is a chance that whatever you put into the hook opening can escape. That style hook relies on
pressure or load to maintain closure. This is potentially problematic in vehicle recovery where the winch cable is cycling in a loaded and unloaded condition regularly as the pulling vehicle or pulled vehicle lurches forward.
Closed system winching, as in a safety thimble or any of the options from Factor 55 that accept a screw pin bow shackle, or this new option from Warn
that includes the screw pin, means that there is no way that the load can spontaneously disconnect under slack line conditions. There is no chance of the hook slipping out of proper orientation and placing the load on that gate, because the hook and gate has been eliminated.
YMMV, but for 4WD winching I'm firmly in the camp of closed system winching. It's clearly the safest bet, and the industry standard now at competitions like King of the Hammers etc.