it was side by side reviews, i seem to remember one by dcrainmaker, he ran them side by side and said the 305 usually got gps lock faster, and its accuracy was the same in almost all tests, other reviews pereferd the buttons as opposed to the touch bezel, the differneces in performance were minimal at best, but still, for half the money it was enough to make it a better purchace for a long time, i certainly wouldnt say the 305 is a better watch, but its every bit as good.