The Z12000 will deliver similar performance to what the BenQ w1070 from 6 years ago delivers.
I remember when I got my first digital projector when they first started crashing in price. A Panasonic PT-L300U projector. It was a 'mere' $2,000. 960x540 resolution. The day after I got it I took it into work. I worked at a local 'high-end' AV dealer that has now gone out of business and I split the signal from a DVD player between my projector and a $12,000 Runco projector. The difference in quality between the two, at 120" diagonal, was marginal. I mean VERY minimal. The Runco bested the Panasonic in almost every single way, but not by much. It was native 720p, it was a bit brighter, it had better motion handling. But, it was at least 10dB louder. In fact, the noise difference between the two was incredible! The Panasonic just floored the much louder Runco in terms of noise level. Pretty shocking. The big take-away from this, was that within the next month 3 of the 5 sales guys who had seen my little test had either purchased the same Panasonic or had gotten a Sanyo Z1.
The point to all of this is that given just a few years the quality of projectors continues to improve significantly and what was once extremely high end, becomes fairly low end. One of the biggest factors in all of this comes from image processing chips. So, the image processing on a 777 was phenomenal when it was released. But that was 2004.
By 2008 when it was discontinued, the image processing had moved towards 1080p, and by the early 2010's 1080p with full 3D support was standard. Now it is moving firmly into the 18Gb/s HDMI resolutions of 4K and everything between you throw at it.
I wouldn't waste money on old technology. It's getting cheap to buy, but if you have a setup already, then... well, it's your money. Certainly those are all similarly good models. But, there's a reason why that SP777 dropped from 10 grand to something like 2 grand right when it was discontinued. The ones that show any image are still selling for $200-$300 online from what I can tell as well. So, it's not 'free' to get into that market. I would rather look for a older JVC and see how it compares. I think I might be more tempted on that instead...
That's native 1080p. Just not as bright as the newer models.