I carried gaming PC and controllers downstairs and tested thee simpit finally wiith X-Plane and IL2FB. I'm not happy with image quality- it's got way too little contrast. Sky looks bright, but ground looks very dark on standard settings. I adjusted the image with nvidia-settings, and with some brutal brightness/contrast/gamma adjustment i got it to look decent.
But i'm still not too happy with it. Looks like i'll have to lend a real projector from work some weekend and see how the image looks with it. If anyone has a old projector for sale (say, <300€) in Finland let me know.
Oh, i forgot to mention that current projector is made of TFT panel and old overhead projector.