I got hooked up with em 7 years ago or so because it looked like a neat product and i was trying to bring something new to the area. Over the 7 years ive installed maybe 7 of their roofs. First few i did they had a rep come up show me the ins and outs of it all and most of it seemed like come sense with flashing and water runs downhill, if it gets in somewhere you need to let it out. Problem im having is i have a costumer that wants one it has 2 valleys and he has major ice dam problems in the valleys. He's retired goes to florida every winter so no one will be there to watch over the house.
Make matters worse he wants gutters installed around the place which will make the ice worse. My concern is the metal valley pan and preventing the bottom from freaking over and water backing up it and running out. Anyone i talk to either doesnt understand my concerns or tells me something wild that doesnt really pertain to what im asking. Its gonna be a shingle over if he decides to do it, any advice. Plz keep flaming to a minimum im fairly new to metal roofs.

And im talking about the granite ridge/guardian shingle, not the batten type roof system.