I have the 660 and considered upgrading to the 665. I found another option recently that is almost free, relatively speaking.
To start, I have the fairing mount for my 660. I turned the bottom bolt around so that the head was inside the fairing, and used a RAM ball 1/4-20 on the outside. This allowed me to use a short RAM arm and a RAM X-Mount.
In the X-Mount, I can my previous Android phone. It has not service, but it will still operate apps via wi-fi. My cell is in the Tour-Pak and set as a wi-fi hotspot.
This allows me to use the following:
Rainy Days -great for quick radar
Weather.Com -Other wx related issues
Gmail- I have a specific email account so I can get emergency messages while riding if needed.
Google Maps- They have a navigator and traffic layers if you select.

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This allows me to have my android device out where I can use the apps, and also keep my phone safely tucked away. I get a new stack of devices every year or so when one of the 4 (soon to be 5) phones in my family is upgraded. If one gets wet and dies, smash it and trash it! I have also considered getting a second 1/8" cord or a bluetooth solution so I could utilize my XM app or Pandora on the phone. So many options, basically for free.
Just something to consider.