When guests come over to play your cabinet, it's best that they have their own coin button. You don't want to explain to them how to shift it (what, is player four going to reach across everyone to press player one's start button, hold it, and hit theirs to get a coin while everyone is playing?), and you definitely don't want to make an instruction card because guess what? No one will read it.
As for load / save, you could always hide them under the overhang of the control panel.
I assumed the player 4 coin macro would be configured so that he has to hold player 4 start button. And if that isn't the default configuration, shouldn't I be able to configure it to be?
I ask because I would like to install a coin door for each player that will serve as the coin button for authenticity...but, still being in the planning phase I may just use a coin door sticker.
And I do like the idea of having a load and save button hidden. If I do decide on coin buttons, I'll probably hide those as well.
I was also thinking of taking 3 buttons away from player 3 and player 4...I can't think of any games that utilize them
I too am new to cab-building, so had those questions very recently...
when planning a 4-player cab (I reduced to 2 after I got my actual donner cab) I was thinking of 4-buttons for p3 and p4. you can look at MAWS for that kind of details, but 4-player is already rare, with 6-buttons is even rarer.
http://maws.mameworld.info/maws/As for coin door, I think you should. Those are fun.
I acquired a coin door (if you go 4-player, you might want 2 coin doors, as the one 4-player coin door is pricey) and altered the coin acceptors to accept anything bigger then a quarter.
I also bought 500+ japanese coins on ebay.
I believe part of the arcade experience is to reach down your pocket for those extra coins and put them in when ready to play or add lives. (just sayin')