The cost of the two systems is similar (RAM & ProClip). The Proclip system does seem to offer greater versatility with the ability to switch device holders fairly easily. I wish I could do a custom mount job like this post: Mounted PB on BMW E34
@ayecon, i forgot to mention this, but if you look closely in the picture on my last post, i had to drill a hole for the headphone jack. so if you get this and intend on using the the headphone jack, you''ll need to drill a hole.
I took a cheaper method than buying a bracket of some kind. I went to the local dollar store and bought a package of sticky velcro squares. I put the squares on a convenient place on the dash that doesn't block too much of the dash controls (between the stereo and heater for me) and voila! A dash-mounted Playbook. The velcro tabs hold quite well and can easily be replaced if they wear out or just plain removed if I don't want them there anymore. And there is no large bracket in the way when I don't have the PB with me. Its an amazing way to use your PB as a virtual assistant while you're driving. With all the hands free laws now, I can still use the PB to check emails etc without having to hold my Blackberry. I can run Megellan, and the car stereo has Bluetooth so I can feed Slacker Radio through the speaker system without wires. Its a sweet setup!