My situation is very similar to your own - I currently have a Panasonic TC-P50GT25 plasma, but also had an older non-HD DLP projector that my wife and I enjoyed simply for the big-screen, movie-theater experience. My selection process for a replacement also came down to either the Panasonic AE7000 or BenQ W7000.
If you haven't already, you should definitely see if you would be bothered by the rainbow effect associated with DLP color wheels. I never had a problem with our old projector's 4x color wheel, so this wasn't a concern with regards to getting the BenQ. I do not have experience with LCD-based projectors, but poor convergence seems to be one of the more common problems, with negative repercussions for 3D viewing.
I ended up getting the W7000 (which is currently about $300 cheaper than the AE7000 right now). It does mean I'd have to invest in more 3D glasses, but the prices seem to drop with those pretty quickly.
P.S. I have the W7000 hitting a 120-inch screen at the house right now, and I'm quite amazed by the picture quality. It'll be very hard to go back to using the 50-inch Plasma.