I'm about to ramble a bit, sorry if I get a little off topic here and there...
I generally stick with skins, because with my EVO thats all that would work the car dock. With this new dock, the Photon can have a smallish case and still work with the dock if the insert is removed. I like that forward thinking from Moto regarding this, and the design of the dock is way better than the HTC one for the EVO. I also like how the skin will protect from a lot of things but add no bulk.
I just got in a number of skins from Phantom Skinz, and applied one to my Photon today. Overall, I like the product. It does make it a tad hard to get out of the dock with the insert in, because the skin material has a slight give to it (a soft plastic vs rigid). I wish that they included a little spray bottle, like ones I got from Body Guardz. They say to get a cup of warm water, add a touch of soap to it and dunk the skins into it. its hard to get just right, i ended up having a bit too much soap i think and theres some bubbles underneath that I dont think will go away. The fit of these skins is great. I've used some that are just a hair too big, and they end up snagging on things because they overhang. the corners where the skin wraps around the unit did have to be tweaked a bit: i had to ttrim a little off and make wider v cuts to make sure it didnt bunch up. There is a skin section for every side of the Photon, including the camera section. it doesnt cover the lens, and the fact that they had a piece for it impressed me. I would recommend this to anyone who likes the skin style protectors, but only if you're quite patient.
http://phantomskinz.com/motorolaphoton4g.aspx