Folks,
I have been using Pharos' product for several years. On a lark, I downloaded the latest version (no trial, I have a license) to my Treo, and los and behold, the screen resized to the smaller footprint. I contacted Pharos and asked them about connectivity to the Treo, and they told me that my old wired GPS could not adapt to it, and recommended a BT receiver. I ordered one, and it connected flawlessly on the first try, and has been working well since.
As a Pharos fan, I'm used to the UI, and the maps scale well to our screen size.
So , I say

to this solution for our Treo (whatever that's worth).
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