ya i understand how it feels when you wnat to know what your model will look like with scales/armours/alpha on them, but sometimes you have to hold onto that urge and focus on the basic model first.
when i wnat to see what my models will look like with alpha, i would normally open up a new layers first before i put them on… this way i can turn it off whenever i move back to the basic model
hope this will help you.
another reason to not to put down alpha first is because it will suck up your workable polycounts… sometimes you can put down tons of detail on your model with only 300k polygons, and if you put down the alphas too soon, it will just take away the polycount on your model and make your model looks mushy even tho you have millions of poly on your model.