I tried switching to MM acrylic flat after years of using Testor and Micro clear finishes. The MM acrylic came out milky on my finish, and dried that way, so I'm gun shy with. On the other hand, I stopped using Micro finishes years ago because the formula was changing on an annual basis, as was the thinner, and you never knew if you were working with compatible materials.
Having spent my formative modeling years along the Texas Gulf Coast, where it is always humid, I can spot the cause of a pebbly or even a spider web result from Testors and other clear flat laquers. In short, don't use them on a day, or in a house, where the humidity is high. I haven't had that problem since I've lived up here, where it is usually dry for most of the year, at least indoors.
And of course, the orange peel you get from Testors is, quite simply, from the fact that you have to be very careful not to spray a laquer (the Testors clear finish) over enamels (regular MM enamel paint) unless it's almost dry when it hits the surface. Same with metalizers, of course, only more critical that they be dry when they are applied. And metalizers do tend to dry between the time they leave the airbrush and when they fall on the model, unless you've really screwed up.