All the optoma's (65 &67n)require a 3d converter(3d-xl) to view 3d. So don't expect that unless you spend 120-220 extra for that and then some more for each 3d pair of dlp link glasses.
I found difficulties with hd70 picking up signals from the xbox and ps3 throughbthe hdmi unless I used the 3d-xl.
Optoma were no help and I had this issue with 2 hd70's.
Personally I find the hd70 a bit washed out for gaming with any background light on a wall(no screen) . Hd 65 better and can't complain about the picture quality for a 720p. The problem is a lot of people on the bay say only 3months old but what they mean is the bought it off ebay themselves 3 months ago. And the hrs they have used not the total hrs ever used. So ask.
Now when the seller says no returns that means nothing (if new or used)you always have 2 weeks to send back under the distant selling act and 40days ebay and paypal protection if something should go wrong.
Now this goes out the window if you collect in person, as ebay say you have checked it. I generally prefer to have it sent unless an amazing deal that needs to be picked up but that's a gamble.
That sharp is a big unit 10kg
SharpVision Projectors: SharpVision XV-Z20000 DLP projector this is more or less the same (one is European one is US model ). The contrast is not really true because it uses the iris for best black and white but not at the same time. I have used it personally but I would imagine has slight bit of noise as a few years old. It is a 1080p so in a dark room will look amazing but its only 1000 lumens that's fine for a blacked out room but useless in day and ambient light for gaming. It is a very good price though I think. But does it tick your boxes.
Another thing about hd 70 is I have had problems with 3, colourwheels and overheating .
Got an hd65 in the corner I bought of ebay with no bulb . Just put a new one in used about 20 hrs few films, MW3 and street fighter on a green wall was awesome. Don't use anymore because use 1080p's now and brighter 720ps but the colour out of the box is great.
If portable and bight is what you need dell are very good , especially m410hd. It's 85% uniformity which is very good, dlp link 3d-ready, 2000 lumens. laser pointer on remote 4000 or 5000hrs in eco ,dlp(may see a rainbow but less goes wrong with it ,colour doesn't fade like lcd) , only 1kg, carry case and if get dell warranty awesome next day replacement(this transferable if you buy off bay).