I would be hard pressed to argue with your logic. For the money, it's a great deal, for the technology, it could pretty easily be considered outdated. I think the Marantz tends to cater to a higher end crowd with some excellent product, but there are value priced projectors out there which likely could nearly match it for thousands less when it was new.
Now with the 1080p models on the market, you can pick up a Epson 1080UB and get true 1080p from a projector with top shelf reviews, and you would likely get a mix of improvements as well as some losses. I expect the Marantz to have better overall processing, DLP color which is great, and punchier contrast. But, only minimally so as the Epson does great on all accounts, and includes 1080p resolution and is very flexible with placement and setup.