Your thoughts on putting an actual working coin door in a Mame cabinet versus a completely fake setup consisting of only push buttons or any variation in-between.
Depends on the cab and on your intended purpose I guess.
I prefer real coin doors myself but I recognize it isn't always practical.
My second choice is to add the coin slot, return and button as separate components. The best example I can think of is Computer Space since those guys kind of had to put it all together without any sort of industry support. Casino style machines are similar but I dislike the style of coin slot/reject they use. But that set up is a real bear to work together right. My test setup has all sorts of problems.
I've only used just buttons once so far, for a retrofitted Z-style (I always forget their damn names) cabinets. I didn't really trust the guy enough to not try and put it on location (he's one of those ---uvulas--- always looking for an "angle" and a quick buck) and I didn't want any responsibility for the cab if it did. The front panel had severe damage so I ended up cutting a new front panel and rebuilding the cab. Far far far more work than I wanted and I'll never do it again. Unfortunately (or fortunately?

) it was destroyed because the dumbass left it out in the rain while he went to Vegas. At least he paid me.

I've never tried to the buttons that look like coin return buttons. Never had the opportunity (or would that be desire?) to use them in any cab.
I can't remember who has a coin door sticker but it's not something I ever really considered. To me, it's kind of like having a car sunroof sticker (Google it, they exist) or those fake auto vents. I consider them... well... lame. Why go through all that trouble to get the "look" when you can just get the real deal?