Hi marco_snijder,
Many thanks for your comments!
A couple of things regarding the 'mismatch' between helmets and breastplates on the green/yellow/black castle footsoldiers: I'm probably going to change a few of the helmets to dark grey (what I think Playmobil calls 'anthracite'), so a few more would match. I would also love to get a hold of more of the light grey breastplates from the 4666 'Eiserner Ritter' special, but I don't know the part number... But in any event, I don't think I want to have all of them matching perfectly. That kind of 'uniformity' in soldiers' outfits was rare and hard to achieve in the Middle Ages.
What I've aimed for is keeping the same combinations of colour and pattern for each group, but with as much variation within the general scheme as I can. Works better in some cases than in others.
Regarding the helmets, I agree that the horned and 'animal mouth' helmets (the second two in your list) are quite unrealistic, with the possible exception of very late medieval ceremonial/parade/tournament armour. But the first two are, I think, not too bad. The first one passes as a 'barbute,' the second as a 'sugarloaf' great helm.
Cheers,
AndrewL