Hi,
I just bought an Epson TW10H. It was between this and the Benq 5120 in my case since they were in a similar price range in my country. The others you mentioned were more expensive so I did not consider them.
Between the Benq and the Epson I found the 5120's picture excellent for the money, especially for totally dark rooms where its better contrast and black level can be put onto the screen.
The big minus for me was rainbows. I could see them and I got a feeling that the slight headache and eye strain I developed after watching was not related to a long day in front of a screen at the office.
I was still thinking about it though until Epson dropped the price of the TW10H significantly over the last couple of week so I got the Epson.
I set it up along with a 2m wide screen over the weekend and I can say that I am pleased with the result and decision. If I wasn't seeing rainbow though I think that the 5120 would give a better picture for DVDs in the Dark.
The TW10H throws a very nice and balanced picture though. The screendoor is there but only if you sit too close. With some ambient light in the room, you can ramp up the picture brightness and contrast to still provide colour rich pictures for watching football or sports with friends etc.
In my case I sit at 3m back and I can barely make it out. Lean forward a couple of feet and its very evident. If only I could bring the wall down behind the sofa and move it back 3 feet or so

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Now on to your questions. You mentioned that you saw a 2x DLP, the X1a,
and you didnt mention if you saw rainbow or not. If not then you are lucky and you have more choices.
Don't use the Svideo output of your laptop. Use the VGA port instead. It will give a top quality signal to drive a projector. I drive my epson through the VGA port.