@lukewells
I finally got around to trying this on my Space Team. Shorting out the Start button does make the Credit button behave like a normal Start button as you said. The downsides seem to be that on power up it immediately launches a single player game. Also at the end of a game when the message "You can continue the game if you press start button within 10 seconds" comes up, if you press the credit button (since the Start button no longer works) it clears the scores and launches a new game.
Separately from the above, on a multiplayer game it only displays the individual player scores once, or sometimes twice before going back into attract mode at which point no matter what you press you can't retrieve the scores, which is a pain when using the game in competitions.
Does yours exhibit the same behaviour as I'm wondering if there are different versions of firmware around. The checksums on mine are 2d92 and 7e59.