In one sense the dilemma (if that's what it is) is surely every managers dream, two top class players competing for the same place?
De Gea's form has been patchy lately he has definitely lost us points, Henderson should now get a run in the first team until his form dips, then David's back in again.
If players are 'taking turns' in any position its bad for them, the manager, and the club and that's why I have never believed in the swopping keepers for cup matches idea. Outfield players get changed, because of opposition, or because they need a rest, keepers should only be changed either because of injury (obviously) or loss of form. Remember Fergie swapping a keeper (Jim Leighton)at half time, in a Cup final I think it was!
David De Gea has, almost single-handedly, won us matches in last two seasons and for a few seasons before that, but this season he has lost us games, certainly lost us the share of points. Henderson is a good keeper, its debatable whether all round he can be better than De Gea, but he has lots of strengths David doesn't... coming off his line and defending his area, are second nature to him... with David its always a problem, will he ,won't he, and the nervousness transmits to the defenders. You only have to watch the opposition at corners and set pieces to see what pressures they put on De Gea.
Two top class goalkeepers, make use of both of them Ole!