Hey Bill!
I saw this one (Navigator) in action last week at the IDF West Pacific congress in NZ. It looked fantastic, and when i did my further research i also saw that note.
The negatives of the Abbott Nav from what i could see was the *VERY* large sensor site - it would be very very difficult to hide it suitably - and of course the fact that the Polymer remains in the skin. The recommended site was on the upper arm on the outside, but as someone who wears business shirts often i know that would look quite ugly.
It's a double-whammy; a sensor that's huge so you can barely hide it, and the inability to rotate between just 2 or 3 sensor sites to avoid that polymer.
Alex