Depending on what you expect you will always get some dulling of the alclad... its an effect and clear coating alters the effect. In saying that however a gloss clear and water based as the alclad one will have less of an effect. If you use a matt clear then the matting base sits on the surface and will distort the reflection.
As for painting between different paint types enamels, acrylics, lacquers, they are not really compatible as theyre different technologies.
I use acrylic clear over enamel base just fine but heres the trick... dont load your paint on. The wrinkling that takes place that
StevenBills was referring to is caused by the loss of paint adhesion and tension.
Go paint a piece of cardboard and you will see it roll or curve up... this is the paint molecules puling together as they dry and expel solvent ( this is paint shrinkage). That process happens on everything you paint but on a rigid surface like plastic or metal the paint cannot bend it up like the cardboard but the point is that paints holding on under an incredible amount of tension and relies soley on its adhesion to not pull off the surface.
Now the crinkling is the loss of that adhesion.
2 products not designed to go together.
We have an enamel painted part, dried, now under surface tension.
We overcoat in acrylic.... those solvents soak through the enamel, wet underneath the enamel and release the adhesion of the paint from the surface. The crinking is now that un adhered film of paint pulling together in the same way it bent up the cardboard.
Overcoming the problem... light coats. Some products will just be far too solvent sensitive and wont take overcoating with anything else. Others you will get away with ok. Most model painting is light coats anyway but your looking to avoid putting on enough product in one application to avoid solvents soaking through and releasing that bond.
Cheers,
Josh