The Panasonic can match and even beat the black levels of the Optoma HD73 home theater projector on the right scenes - those that are very dark AND do not have any bright areas at all, but on every other type of scene, the HD73 is just plain better.
The HD73 is also rather bright, it can't match the PT-AX100U in brightest mode, but if you compare "best" modes, the Optoma definitely puts out the same kind of lumens as the Panasonic projector.
The HD73 projector is a typical lower cost DLP, in that the zoom has very limited range, and there is no lens shift. If the HD73 had lens shift and a siginficantly wider range zoom, it just might have taken the top spot in this category. Build quality, like most under $2000 projectors is not sensational, you just don't get the feel of a Mercedes. Adjust the zoom, and it goes out of focus... that type of stuff. Of course once you set it down, or install it, you only have to adjust the zoom and focus once - so no big deal. Like its predecessor, the HD73 produces a very watchable and enjoyable image on movies, especially the new hi-def formats, and plenty of brightness helps it look great on sports and other TV content. Its 2 year warranty is industry average.
Optoma HD72 Home Theater Projector
The HD72 DLP projector (identical looking to the HD73) has been around for about a year, and when launched it was the brightest of the under $2000 projectors. Optoma has not indicated how long it will remain in the lineup, but considering the HD72's popularity, and past Optoma decisions on very popular models, I doubt it will be going away very soon. Today, the Panasonic PT-AX100U and Epson Cinema 400 are even brighter, but primarily in brightest mode. In best mode the HD72's measured 518 lumens still makes it one of the brightest in good movie watching mode.
The HD72 cannot match the HD73 in black levels and shadow detail, and color performance out of the box without adjustment isn't as good, but the color balance is easily correctable with a basic end user friendly calibration disk.
If you like that "film-like" quality that DLP projectors are known for, but need significantly more lumens than the HD73 provides, and are willing to give up some black level performance, then the Optoma HD72 is an excellent choice for those who find it can be positioned properly in their room.