Are you sure you are seeing SDE and not the screen texture due to the light canon the 5010 puts out?
I had an Elite screen that would look like SDE but I would pause it when I thought I seen SDE but then discovered it as I took a closer look that it was the screen texture being exposed under the high lumens.
EDIT: Ok, I see why you might see SDE. 7 feet from 120". Seems being that close would be a chore for the neck.
And my wife thinks we sit too close to our 117" at 11 feet.
No, 3D is amazing. Close enough to perfect for me. Actually I very rarely saw SDE on my 720p Acer 5360 in 3D. I also think SDE is a factor of brightness, so your 1.0 gain screen should be good. I am 7' from a 105" width screen so am really close. I like the IMax effect. I will pick up an ND filter sometime. I am sure that will help. I have a 1.0 screen that is too small, but should make for a good test.
I am not unhappy with the Epson, on the contrary it is a fantastic projector mostly. I would highly recommend it for pretty much everyone but me I may get used to the SDE in time too. The Silverstar is a great screen except for a sheen on bright scenes. I have gotten used to that so it doesn't bother me either. Perhaps a pulldown 1.0 screen for 2D may be the perfect fix. Still, I wouldn't need that with the Panny.
The HW30 sounds like a good projector too, but the Epson and Panny are the only projectors that crank up brightness for 3D so it approaches or equals 2D brightness.
It arrived yesterday. Other than its very loud buzzing-noise it's great. Guess i was not so lucky with my unit. Anyway this is my first projector so I don't have much to compare with about the picture quality. The smoothscreen is awesome. The difference feels just alike when I upgraded my PC monitor 60hz to 120hz. Don't know how i survived without it. Too bad it doesn't work with the game mode on, really a bummer.
Haven't tried 3D yet so I can't comment on that. But as what pretty much everyone else say I guess it's great too.
You are talking about frame interpolation. Smoothscreen is a physical lens device that spreads each pixel out a bit to fill in the black spaces between. Without it, like on my Epson 5010 sitting at 7' from my 120" screen I can clearly see the black spaces between giving me a screendoor effect.
It shouldn't be giving you a loud buzzing. Make sure high altitude is off, if on it cranks the fans up. Well, unless you live at a high altitude of course.
Because the way FI works is looking at the last frame of a movie and the next frame and calculating a good pixel in between for each frame (2 million pixels) so you are at best a full frame behind before you show something. This is lag you don't want when you are gaming.