If you use multi textured models, then the shader is not really being used as if it was a single textured model.
You wont be in control of the normal and spec, as they will be faked in the engine.
If you can remap the object to be one texture it would be better.
If you want to use light mapping, then no more then 6 textures, or each one over that number will be the first texture.
If you are going to just use realtime lighting then, I have seen up to 12 used with no issues.
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processor(s), 8gb RAM, Nvidia gtx660, Windows 7 Pro 64bit, Screen resolution 1680 x 1050.
