Anthony,
You've raised this possibility before. It's definitely not a problem at seat level on a GRP BR20, where I will be sleeping, as any moisture will be captured by the aft locker drainage channel (just in from the rear of the tent - see photo 4 in the instructions). I can see that the ply BR17 seats and lockers are different, so it may be more of a problem for that model, depending on trim.
It could be a possible problem on the BR20 cockpit sole in flat calm conditions, again depending on how the boat is trimmed. If the outboard fuel tank and other heavy items are moved towards the stern and there are waves, then it is probably not a problem there either. Real users (including me) will report back in due course. If this summer is anything like last year's, there should be no difficulty finding challenging conditions to test the tent in.
Graham