Brian,
It is a good idea. I like the idea of multiple buttons though...like I said, one for each player. My questions about the all-in button were based on incidents when a player would go all-in without declaration. If the dealer does not notice that the player is all-in, and the dealer controls the all-in buttons, he's not going to put it in front of the player.
We're getting a bit off topic, but the all-in certainly effects showing cards at showdown.
This is definitely something that can be worked out. I will repost a suggestion that I made four years ago: "Whenever a player pushes all of their chips forward, or goes all-in, they MUST declare that they are all-in. Failure to announce an all-in wager, or make your intention clear, will result in a penalty, and possible forfeiture of uncalled chips. If deemed the winner; there will be no financial gain from the unclear all-in. The use of an all-in button is encouraged, however, this will not shift any responsibility from the all-in player to the dealer."