I've been aware of those matchups for awhile having seen others mention it before. I'm generally a WW defense guy, play a lot of matchups, and it usually works out pretty well (unless it's Miami last Monday night. I blew that one).
Right now Zona against the Lions and Rams looks pretty good (although I won't be surprised if Stafford's Lions are clicking decently by then since they've already shown good signs). I'm not sold that you can't do better in week 14 though , playing against SF in SF, and you have to win that week for the other two games to matter. Still, it's not like it's the Colts or Packers offenses.
I just looked at the schedule for the pre-playoff push and it looks pretty good too. Home v MIN in week 13 kinda sucks (unless Favre is tossing INTs again by then), but week 12 (at TEN and likely Vince Young by then) and week 11 (Rams... weird that they play each other weeks 11 and 16, both so late in the season), and week 10 (home to Seaquacks). Not bad at all.
A lot depends on your league's WW rules. If you have to lock down your roster by week 12 or so, getting Zona early seems like a good move. If you can't get the Zona D, at that time of year there are often nice situations available that don't exist yet, usually due to injury to or benching of a starting QB.