I tore off most of the old roof and getting ready for the new... it was closed valley 3 tab. I'm going with either Timber dim or CO dim. I don't know if I want to bother with the cement required with open valley, but the dim is thicker than 3 tab:
Is it harder to do a closed valley with dim shingles? I'm in Sacramento, CA and it'll be mid 80's when I do the roof. I have a heat gun, will that help to get them to bend without damage?