MAMEWorld Forums - EmuChat - [exzisus] Documentation: possible prototype?

I noticed that exzisus is very different than its clones. Since it's the parent set, one would probably assume that exzisus is later than exzisusa and exzisust, or at least contemporary.
A lot of things have been changed between these versions, but some could be considered as programming choices (i.e. barrier powerups, bigger and faster enemy bullets, destroyable options, etc.). Some other things, though, seems a bit strange to be in a later or contemporary version:

- The levels are shorter; in each level you can get to the boss in approx. 2 minutes, while in the clones you need almost 3.
- Weapons (D and L icons) go straight to maximum power by getting only 1 powerup; in the clones you need at least 4 to do that, and they have to be the same icon.
- Many attack patterns are too simple, with the aliens just traveling the screen at full speed; the clones have complexer attack patterns with sophisticated trajectories.
- Some level hazards are easier. Ice poles (level 2) can be completely eliminated, and the expanding-contracting body (level 4) is slower and more predictable.
- Play area is almost unlimited, you can fly so high to cover the HUD. This can also be exploited: if you have the A(erodynamics) powerup, you can pass over most level 4 hazard without being hit (screenshot). In the clones you can't do that, the play area is limited just below the HUD.
- Level 2 boss has an obvious typo (screenshot).
- This bug.

A couple extra considerations:
- The clones exzisusa and exzisust have only one different rom (b23-11.7f / b23-15.7f) which has one different byte, used to display an alt copyright. A game is usually licensed, and changed like that, when it reaches its final version, right?
- Exzisus uses a dedicated cabinet, which is probably more expensive than a standard one. Maybe they produced some, possibly for location tests, then dropped the idea when ready for mass production?

All the above things considered, is it possible that exzisus is an earlier release or maybe even a prototype?