Actually, I've made it safely thru' the Channel (Jan '40) in my 2nd patrol since installing GWX. The hardest part was the choke point between Dover & Calais. I encountered I DD, 2 MTBs and 2 armed trawlers & despite diving & going silent running was still detected. The depth charging wasn't too aggressive tho', but I did sustain minor damage to the port prop shaft (?) or something like that. I managed to give them the slip after about 2 hours or so game time.
After that it was clear sailing. I encountered 2 French ships which I sent to the bottom

for a total of 12000+ tons - it was a large merchant and a small one.
I've now exited the channel and am somewhere on station in the N Atlantic - BE44 to be precise, my assigned grid.