I saw the "safer" claim and I guess your could make a case for that - if you had something with enough power to rip the rubber isolator pads apart, and it does happen.
They're called "spools" because they have an outer ring that, should the isolator fail, will prevent the engine from lifting too far under torque.
Here's a link to Mancini Racing who sells them with upgraded poly isolators. For the price, the k-members not a bad deal, but I wouldn't be swayed by the 'safety' pitch as a torque strap on std mounts will do the same.