it would certainly make the center bulkier where all the seams meet. Depending on the weave and how it frays, you may need to make the seams larger but you can check fraying when you make your drapes...also, it will be heavier, as you say, and you may or may not want to add batting depending on your preferences. also be sure to wash it first since many decor fabrics are made for drycleaning and not washing.
I'd probably use it but not on something with center point multiple seams like on the OBW.