I have a top loader modified to output composite video. I've compared it side by side with my toaster and the difference in picture clarity and color is noticeable. It hasn't stopped my from using it though. In fact, I probably use the top loader most of the time because it's quick to pop a game in and out of it and it's rock solid reliable. I've never had it fritz out on me in the middle of a game. I personaly don't believe the 72 pin connector in it is any different than the one in the toaster. It simply benefits from not having the spring activated mechanism the toaster uses and so there's nothing to shift or move while playing to cause the screen to fritz.
I've always wondered if it wouldn't be possible to modify a toaster to eliminate the spring mechanism altogether and get it to run, possibly while it's still in the game load position.