Yes the case reduces the reception a bit. But not that much. I have "the other" metal case. Not the one from Proporta but I can't remember who made it....
Don't forget that reception will sometimes change depending from the place were you are. There are several places on the road were reception is bad and sometimes I can be sitting at one place and have good reception and suddenly it is almost gone . This is the providers fault :evil:
Wouter