In reply to Andy Cloquet:
I can confirm that my wifi and 3g connectivity goes down drastically when incased in my otterbox defender. I have never had a problem making calls though....
I suspect you are right, its just the nature of the increased shielding of the anetenna, and would be similar whatever you went for.
The defender is however very easy to remove, and very effective (although not completely waterproof). I tend to use mine when out in the field, but remove it when knocking about at home.
Cheers
Trist