I can say a double Amen! at least to the first part of this statement. After I replaced my attic RS 15-2160 with a 4228, my UHF digital reception improved dramatically. And it makes me wonder whether these Forum musings that attics block signals 30, 60 or higher percent -- and made by knowledgeable members but always causing me to cry out that that's far my experience -- but whether these attic signal blockage musings may be based on the most absolute worst case scenarios. My experience is that, with signals coming in almost exactly perpendicular to my house from great distances, shingle and plywood do little blockage. Now an incoming real oblique angle might raise roofing nails, etc. questions.
One other point, with the horrible winds I get at this elevation, I've always been concerned about putting any antenna on the roof. Forum members seem to say not just generally, but absolutely Yagis put less wind load on masts. But since I never tried any on the roof, I'm wondering if under certain conditions a 4228 for example could be as accepting of winds as for example one of those longer 100 inch or so Yagis (an XG91 for example).