This unit did turn out the be defective. The antenna did not connect internally and I sent the unit back.
But as TABirdman mentioned above - there is and has been a difference between the Handheld units and the desktop units - and not just in the RSSI settings. And this is an issue between both the Radio Shack & Whistler units (since Whistler makes the Radio Shack units).
What complicates this more is that the "Easier to Read" bible everyone so praises makes this even worse by suggesting that the default RSSI settings are actually too low by default?
So I highly recommend that folks DO NOT clone settings form the Handhelds to the Desktop units, UNLESS yo go back and make the appropriate changes in the Expert Setting sections!
So what I did was:
1. I took a screen shot of both units in their factory default settings.
2. Built, Programed & Loaded the Handheld and then saved the settings in a external file.
3. I then loaded those programing and settings back in to ARC500, reset the Expert settings back to the Desktop's defaults and loaded that into the Desktop unit which is now a Whistler WS-1065 (RS 652 are no longer available).
Everything is now working great and as expected. I am sure that I can probably tweak the settings even more based on the Easier to Read page, but honestly after all this, I don't really trust the data that is over there and I don't have enough experience to know what every little settings - so I am just going to stay away from it for now.
I'm happy with the reception I am getting - I am picking up signals as far as 30+ miles away and even excellent reception of Search & Rescue missions in the mountains.
That's my 2 cents.