I bet you could get that down to around 5 ounces too.
I took a LowePro Toploader Zoom 45 AW and removed the straps and rain fly, cut off the top handle, sewed that webbing into small loops in case I wanted to attach something, and cut off the front pocket to get it down to 5 ounces even. It is basically the same model as your case, and was about the same weight without the straps. I clipped two mini carabiners to the D-rings to hang it from my shoulder straps bringing it up to 5.3. I may replace the zipper pulls to see if I can get it back down to 5 even.
IMHO, 5.3 ounces for a fully protected DSLR case is worth it.