Hi Jan,
I have worked with ewa-marine now for about 10 years. Allways freediving. I had 5 different housings for four different cameras. I once had a leak, but since it is a clear plastic bag, you can easily react.
Here are my opinions:
1. You can buy a new F828 for the price of a rigid housing, so why do you fear.
2. A rigid housing is also subject to flooding.
Disadvantages:
1. Buoancy. Especially in the consumer digicam housings there is no possibility to attach weight.
2. Visibility of the display: near zero, so you dependend on the smaller viewfinder and it is not easy to control whether a shot is good or bad.
3. Sometimes it is hard to operate several buttons
4. Moisture. Even extensive use of silica gel sometimes is not enough, especially when descending during freediving.
5. No use of external flash with consumer digicams.
I now bought a sea and sea housing, simply because the U-AXP 100 has a too high buoyancy, even with 1,5kg lead weight in it. It is very easy to handle, compared to the ewa marine pendant. But if flooding is your only concern: I use a canon 300d, and could afford 6 - 7 camera bodies for the price of the complete set. I still use Ewa-Marine for my video camera (along with a DIY framework and a kowalski lamp attached). The boyancy of this one is perfect, and so is the handling.