Combining Standing Seam with Shingles

Hello, I'm a builder in Michigan with a summer home project in Ontario, Canada. I recently spoke to a standing seam roofing contractor that described a roof composed of 36" (+-) at the bottom of the room, 24" wide metal valleys, and the balance of asphalt shingles. The intent of this combination is first to address ice build up, second is ice and organic debris build up in valleys, and last is having a better roof without the cost of all standing seam. I candidly had never heard of this combination, however this contractor said he saw it displayed in a magazine recently produced by a Standing Seam Roof Association. I'd be very interested to learn more about the merits of this approach, and who has done it successfully. Thank you, Dave McCatty (248) 548-1010