After noticing this, I decided to measure the length of the idlers themselves. The plenum idler is 1.345" and the block idler is 2.370"! That's damn near the same length as their stud's unthreaded sections! And what that means is if the installer A)doesn't install the stud(s) fully into the plenum/block or B)doesn't use a washer under the nut, the nut will bottom on the stud threads and it will be almost impossible to properly preload the stud while torquing the nut. And if that happens, it should be no surprise to anyone that the stud would eventually break from fatigue.
The longer threaded sections of the ARP stud remove the possibility of the nut bottoming out before tightening on the idler even if you don't have it all the way into the block or the washer under the nut. As for ARP vs OEM, I'm no rocket surgeon but if BDE doesn't see a problem with them and I don't recall any of the Z performance shops saying there is a problem with them then you're probably spending an extra $20 for the peace of mind of more bigger more better tensile strength. But it is only $20 which in Z money is basically free.
Studs normally don't have a torque spec because the torque comes from the nut on top. Red loctite should be used only on things you don't intend on taking apart. If you're going to use loctite use blue.