Harmon has been pretty good in a reserve role. Not too worried about starting him instead of Gregory, though he's obviously more of a FS type and they'll lose something in run defense.
As long as Gregory's back in a few weeks and Nink/Dennard's injuries aren't too serious, it's ok.
Gregory is not (my) prototypical SS. I think Harmon will do fine - could even continue to improve. Gregory's experience could be helpful against Manning.
Clay Matthews was out 4 wks with broken thumb, that time-table brings Gregory back (too early) at the Houston game? At that point we'll be playing struggling offenses? Might not need him then.....