The short precise 2way joystick with close by reverse button is an important part of re-creating the original feel of the game. And it will perform better than a longer microswitched stick. We use our own 2way joystick.
It's not easy to incorporate the Defender controls into a general purpose panel, and this is the reason we developed the swap panel system.
On the standard Defender panel below we use proper leaf buttons for all 5 gameplay controls (thrust, fire, reverse, bomb, hyperspace).
DefenderPlusLR (Left Right)
This panel starts out as a Stargate panel (Defender plus inviso). It has our 2way joystick to give you the best feel and control, and proper leaf buttons for thrust, fire, and reverse (You can upgrade the others to leaf if you like).
And then we add Left/Right buttons. This lets you play games such as: Galaxian, Asteroids, Phoenix, Space Invaders.
Available in various colour schemes: Original (inc Green), Red/Yellow/Blue, or Red/Yellow
A spinner fits neatly into the middle of the panel. This adds Tempest, Arkanoid etc.
The Left/Right buttons become a second set of action buttons ( eg Fire/Zap) to allow either left or right handed use of the spinner.
A 4/8way joystick can be added to the middle of the panel (quite a common position on single stick arcade machines). This greatly expands the number of games playable without needing to swap the panel with no degradation to the Defender experience.
If this covers all the games you are interested in, then it makes a cost effective Single panel machine by avoiding the need for storage compartments.