Use multiple materials?

So I have a few smaller objects that make a complete ‘thing’. Some of this thing, I want to use different types of shading. All objects are mapped onto the same texture. So, in order to achieve this, should I use a separate material with a different shader assigned? Or should I try to figure out a way to write a custom shader? I basically would need 2 alpha textures in my case, whether from the alpha channel or stand-alone textures. Because in order to use one shader, I would need, in my case, to define a gloss area, and a specular area, and their levels. Not sure whats best performance wise, or what.

I think that the easiest way would be to use a different shader for that part of the object together with your original texture. Actually you could also use another shader like the particle shaders (Particles/Alpha blended) which will recognize the alpha on your texture and use it. This might be better for the performance but it also depends on the size of your model. You probably should try both and then decide which works best for you