If Gase is the HC in SF, I don't really have an opinion about it, not yet. To me he is like Quinn. Gase might have called plays in Denver, but Peyton was the real OC. Quinn might have called plays in Seattle, but Pete was the real DC. It doesn't mean either won't be a good HC, but it does mean the resume has been padded just a bit.
I will offer this: If Gase is being trusted to bring Manning's offensive ideas to Kaepernick, I love the hire. For the Seahawks. Trying to bring both Peyton's pocket presence and uber quick release to Kaepernick seems a little like importing pork to Israel.
If, on the other hand, Gase is good at creating around player strengths, good for him and the Niners. I think there will be no way to know that until the Niners play actual games.