That my dear friend is the million dollar question. Each one has in its own right things I like and dislike. BTW, I have the Bionic Lapdock not the Atrix one.
As mentioned in a previous post...
The Bionic Lapdock,
It is way better looking, thinner and a slightly bigger screen.
Double Tap on Touchpad to enable/disable it. (Helps when Typing)
Photon hangs a bit off the docking area.
Photon does not attach to dock with a cover.
Screen does not tilt further back (like the lapdock 100)
No dedicated multimedia buttons.
No two finger scrolling on touchpad.
The Lapdock 100
Screen tilts further back.
Phone stays put in docking slot.
Dedicated multimedia buttons. as well as Call, Print Screen buttons
Extra rows of keys
More keyboard space, smaller touchpad.
Cable is abit stiff.
Due to length of cable, Phone sits in docking port that when playing netflix is upside down (unless you do the netflix hack)
Screen is smaller.
Bulkier design (some say it looks like an old Brother or IBM typewriter)
No Double Tap on Touchpad to enable/disable it.
More observations on the lapdock 100 can be seen in this AF post
and more observations at the Motorola forum thread
Anyway, going back to your question, for me the answer is that I end up using both. One day the Lapdock 100 another day the Bionic one. But since the Bionic has a bigger screen, I do tend to use it a slight bit more than the 100. (Which is why I want the 500, besides its vga port).
But all of this is temporary until I get the Lapdock 500 after the holidays. Being that its been confirmed that the Photon works with it, I'm surely getting it.
(At this rate I can open up my own Motorola Lapdock store, with so many lapdocks lol
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