I used Superdec Satin on my front door a few years ago. Found it nicer to use and really appreciate the water cleanup compared with oil-based. We'll see how it holds up but looking good so far. I also took the door off but I think it would be fine in place too.
+1 for Zinnser Allcoat. Have just painted a load of cladding and am about to do a door (if it ever stops raining for long enough). Good stuff and you can get it in any RAL colour.
I don't recommend the oil based allcoat - horrible stuff - really smelly and very difficult to work - really 'draggy' and impossible to lay flat - once on, very little time to rework - I gather the water based stuff is better.
I used Superdec Satin on my front door a few years ago. Found it nicer to use and really appreciate the water cleanup compared with oil-based. We'll see how it holds up but looking good so far. I also took the door off but I think it would be fine in place too.