In the playoffs the Broncos defense has gone up against the #2 and #6 offenses by pts/drive and given up 17 and 16.
Seattle has faced #3 and #12, giving up 15 and 17. The two teams' defenses are not playing that differently right now.
I'd actually take our run D and corners over Seattle's. They definitely have the better safeties and probably a better pass rush. A pass rush can be neutralized by Manning, though, and their aggressive man coverage could be exploited by our "rub" routes. So the refs letting them play could help Denver's receivers just as much.