I dont see why running A common ground from an I-pac, J-pac, Opti-pac wouldnt work........However I would check with Andy first as it is his product and I would hate to say yes and have it cause an issue. However theoretically It shouldnt be an issue....
I tested my I-pac and the grnd terminals on it do have continuity with the computer chassis that it is plugged into, So the I-pac is sharing the common ground the computer/powersupply is using.