"Light weight troughs work fine when you solve the ice dam problem from inside the house. High pitch metal roofs should have a snow gaard to stop the snow from sliding down. "
Even new houses in my area had ice dam problems due to the ice storm. Many people had leaks and damage from gutter ripped right off from the weight of the snow and ice. Others had wet spots down the side of their houses where water had leaked in. Nice houses too.
In my case there are plastic stoppers on the metal roof, guess what? they got ripped off too! Actually there are part of the problem. This year i plan to take the rest of the survive stoppers off completely. The ice and snow should slide off easily as to avoid forming a large mass as it did this year. The stopper or blades are not a good idea at all IMO. Same with heating cable, one house caught on fire because of them.
"It would also be difficult to get them to drain properly if you're relying on flexible cord to hold them up. " That part should work, if they arranged on a slope and tie the bungee tight. But it will look ridiculous.
Another neighbor says he has hangers or clips and takes them off in the fall. That might be the best idea. I guess the bungee might not be that great for re-sale value. LOL. Some sort of fail safe or stretchable hanger would be ideal. If the is 100 lbs of pressure there the hanger should fail, how hard is that to design? Why don't i just sabotage the hanger, cut a bit into the metal so it will break off?
There is that time in the spring and fall when it is a bit of ice and rain. I guess i can live with that. Actually my 'house skirt' --3 feet of poly on a slope around the circumference of the house seems to work fine. Except this year there was so much snow and ice build up around the house there was a mini flash flood and the basement flooded. It was big clean up to scrub the entire basement down.
What i plan to do is raise the slope a bit higher with grave this year and finish with patio tiles and bit of sand. Maybe some interlocking
This should make it really tight. Also a some weeping tile just after the poly ends, a trough with sloped gravel and pipe.
The key will be to remove all the snow and ice from around the house on a regular basis.
The eaves drought would be some extra protection for $100 or so it is cheap protection but not if it rips of the fascia off. That was very hard job to get the flashing around there in nice way.