It's been a full year since I've had my hands on a Panasonic PT-AE8000U. Still, this is an easy comparison. First price. The PT-AE8000U is in its second year and is now officially $2549 down from the original $2999. Panasonic has a promo running now, for 2 pair of glasses, so overall, the two projectors are priced close but there's still more with the Epson, including lamp and mount. Panasonic has a promo currently providing a 3rd year warranty, but they do not have any replacement or loaner program.
From a feature standpoint the Panasonic definitely has the edge, with its lens memory, and creative frame interpolation, plus all that fancy stuff, such as their signal monitor.
Placement flexibility is about a tie. Epson's lens has a touch more range, and so does their lens shift if I recall correctly, but there really isn't a significant difference. That is, unless you want to go wide screen with a 2.35:1 screen, which the lens memory allows.
Now let's talk picture. I'll give the slight edge here to the Epson. I think this 4030 definitely calibrated better than the PT-AE8000U that we worked with. The other aspect, of course, is the black level performance. I won't make a firm call based on comparing images, so I have to take my best guess. I have watched the 4030 against the Epson 5020UB, and I remember about how much better the 5020UB was compared to the Panny. My take is that the Panasonic and the Epson are pretty close to tie. I might conjecture that the Epson gets to a slightly blacker black, but Panasonic doesn't put as much range into it's iris, so the PT-AE8000U might have better blacks in brighter scenes.
Overall, I tend to favor the look and feel of the Epson projectors (a little more pop to the image) over the Panasonic's but it's really close. Today though it comes down to taste, because of all the dynamic features like Epson's Super-resolution.
The only big difference is that most Panasonic owners buy online, and get their support by phone or online. Everyone buying this Epson is working with a local dealer. So, if you don't care about that, or the replacement program, or a particular feature they are close enough, that you can take your pick, go with your instincts.