On the issue about where they recommend the placement of the arrestor, I am glad someone else besides me thinks it should be installed outside before the line enters the shack. Shouldn't a quality transmatch be able to match the transceiver output to what the arrestor and beyond presents to it?
Ed, I get the sense that you're not understanding what Steve said. Yes the arrestor NEEDS to be outdoors, just like you've described. Now you've got your rig and tuner inside the shack, the coax goes outside to the arrestor and then out to the antenna. The arrestor on it's own will give you a 1:1 match, no problem here. But if your antenna presents more than 5:1 SWR then as Steve described, there may be high voltage on the coax due to this mismatch and the arrestor may fire and direct that voltage to ground. Now your tuner will be doing it's job in that it is faking a SWR of 1:1 for the rig. That's what tuners do, they do not change the SWR out at the antenna, they just fake it so that the rig sees a lower SWR. Now the problem the ICE is mentioning is that if their arrestor fires to ground when your transmitting, then you'll in effect be shorting your transmitted signal to ground, which is a no no and could ruin your gear.
My suggestion is determin what SWRs you have on your antenna and ensure that none of them are higher than 5:1. If so, then you'll need to not operate on those bands with that antenna, modify the antenna, or change the antenna. The arrestor is a good thing and should be in place. Hope this helps. Phil KB9CRY