I too would be interested in how you like the Semsons.
I currently use the Arkon Powered Universal Mount with a USB to MiniUSB adapter (included).
I like that it has two USB ports, and it also has a integrated amplified speaker which I use with my navigation/GPS (recently working on my Mogul, yeah!) for LOUD announcements.
I also have a Bluetooth GPS that charges off of the powered mount.
I use the long gooseneck and it works great, been using these Arkons since my Treo 300
http://www.arkon.com/poweredpdamount...Feat=universal