Everyone I've spoken to has said the "compatible" cartridges are identical to the original ones. No difference in the print.
I'm just gonna stick to my game plan. I'll go with originals. I just recently scrapped an 8300 with full 700ml inks. I kept them just in case. About a month ago I ran out of a color. I inserted the 700ml I'll tank from the 8300 and it recognized it and it worked. Last night I ran out of another color. I inserted the 700ml 8300 tank and I got an error saying ink not recognized. There's a company online that sells the little chips to swap onto the 8300 tanks so the 8400 recognizes it. Anyone ever done this before?