I have a love hate with Defender. In 2006, I built a multi-Williams game. You'll notice the green button for Stargate Inviso:
I got rid of it in 2009. I didn't like using a 4 way for Defender and the reverse button was a little too far away.
In 2012, I built another defender. This time, I bought a NOS defender 2 way stick, and I put my controls exactly where they should be. I used a PC and Mame. It was good, my buddy has an actual Defender and Stargate. In 2018, the computer died and I replaced it with a 19-n-1 and Jamma.
http://And in 2020, I extended the sides of the bartop and converted it to a cabaret machine. You can see on the control panel the inviso button is there, but I have Stargate available on the 19-n-1. It boots straight into Defender. I can't manage Stargate. Like you said Neg1, too much stuff going on
So, to Jenns point, for me there is only 1 way to play Defender, and that's with proper controls. I love the game, but I'm terrible at it. I don't know if original hardware is better or worse than the 19-n-1's, because I'm not great at either. I have yet to break 100k.