I have been experiencing some problems with my TTL connector in my housing. The Dutch distributor kindly offered to change the housing for either a new DX350D or for the DX400D.
I went to check the DX400D and see whether it was worthwhile to swap the DX350 for this new model.
In my opinion, the main new features of this model are:
Built-in TTL converter
The built-in TTL converter saves some space outside the housing and the slight additional weight that the external TTL converter puts on the left side of the housing.
There is a button inside the housing to switch between Manual and TTL. This can only be chosen before the dive. The other drawback of the internal converter is that you are not able to choose flash compensation as with the external TTL converter.
This TTL converter uses a flat battery which will be in stand-by when the strobes are off (will still consume energy even while you are not using the camera). I called Sea&Sea Japan and they informed me that under "normal" use conditions, the battery should last approximately 1 year.
The DX400D only has one strobe connector on top of the housing
Optional magnifying .8 viewfinder
The DX-400D uses a different viewfinder which allows you to upgrade to a .8 maginifying viewfinder instead of the .66. I assume that in the future there might be a 45 degree viewfinder for this model (just an assumption).
Buttons on the back of the housing
Until so far, I was more or less convinced on changing from the DX350 to the DX400D. The problem arose when I checked the buttons in the back of the housing.
To my surprise (shock?) a couple of buttons just disappeared in this new "improved" housing. Namely, the menu button and the delete is gone. Also the display button is gone.
This took away all the doubts I had whether to change to the DX400D housing. As an example of a big disadvantage, without the menu button you are not able in the 400D to select a picture to do custom WB. With a small adaptation of the DX350D housing you can use the 400D camera with all its features.
I cannot understand what made Sea&Sea develop a new housing where they take out such important buttons (they were there in the DX350, you just needed to put them to the side!!!)
The TTL inside the camera makes the camera more streamlined (also with less air inside the camera, meaning more negative) but gives you less flexibility in using the TTL.
IMHO, this housing is a no go, at least until the other buttons are added to the housing.
Any comments, please email me.