You'll have to wait until the firmware is updated because Benq w7000 had to fix a pixel mapping issue on the HDMI port with the firmware. Go see a Benq w6000 instead, they didn't have this issue. I believe the Mits had a pixel mapping bug sort of like the Benq w7000 but different (Zombie helped Benq fix), so next firmware update the w7000 will be the same as w6000 sharpness.
The Benq's focus uniformity seems to have some variance between units, but I've never verified that myself, however assuming a good unit, it should be a tad sharper than the Mits hc7800, especially if you saw a Mits with a sharpness bug.
I owned a Mits hc4000 (hc7800 has better lens), and it was fairly sharp, but the focus uniformity wasn't perfect, it was off enough to be barely visible in Video. On the w6000 I saw, the focus uniformity although not 100% perfect, the center point was just so ridiculously sharp that focusing the PJ at about 1/4 screen width point made the image sharper than the other PJ's I've seen. It was definitely sharper than any other projector I've seen close up. I have seen super expensive DLP's in showrooms (didn't catch all the models), one was a Runco LS-5 I believe, but I would have needed test patterns to determine anything. I was at Fry's when I played with the Benq, but I brought a disc with me and the guy let me try it.