Why you want to use different material type ?
Material type is base of material master record. Material type controls many areas for a material master (Like as number range, valuation class, price control, value and qty update, internal and external procurement etc etc)
If the controlling are for the material is same for your all material, then please do not use different material type.
You can use other field like as material group, External material group, classification etc. to differentiate the material master.
By the way, if possible then you can use different material type for your requirement. Nothing will be disadvantage at all. If you control the data and all different things of material type, then you can use.