Part III: Comparison
I have an original G1 release to compare off of. By looking at the leg stamps, it's not quite the same toy which was reverse engineered for the reproduction.
The original's stamp:
The reproduction's stamp:
First, we'll cover the bot form!

Again, please note the tightness of the figure. I'm able to produce gravity defying mid-transformations because of the build quality. The original (played with constantly 21 years ago), just flops.
Original
Reproduction

The reproduction's paint application is thicker and cleaner than an original release. Of course, there's about 20+ years of process improvement behind this ... but still, a positive is a positive.
and onto some various angle side by sides.
And just a random note ...
The front axels on the original are a dark metal. On the reproduction, they are also a dark metal, but with a dark chroming placed over it. Be cautious of the rocket launcher clip, as it may scratch the gorgeous finish.
Onto the car mode!

Right away, you can see that the "26" on the nose is no longer a factory applied sticker! It's painted on to reveal a seamless look.
The red / white stripe on the top is now also painted on! So long are the days of crooked application. Also, no need to cut a sticker at the figure's midpoint. No need to worry about applying the sticker to an uneven surface (there's a small ledge on the rear panel).
To me, these are Encore-like improvements.
Also, not pictured, but on the original ... the "Ciantes" on the right side wouldn't line up either. There's a gap I just couldn't close. (mentioned in Part II)

The spoiler is completely locked into place. With the original, that's the only position I could make it hold.

Here's a random belly shot.
Comparison Conclusion:
There are significant "upgrades" to this figure when looking at the original. "Upgrade" is a perceptional thing, but from my view, the painted on (previously factory stickered) details are terrific.
The construction is of the same quality. The materials are greater than or equal to the original.
Comparison score: 5.0 / 5.0
If there were ever an Encore Mirage, this would be it.