Sharing my first experience with projectors:
I have tried Vivibright GP90 (Rs.16-17,000), Egate P513 (Rs.17-18,000) and Epson EB-X31 (Rs.34-36000).
Having tried Epson, I could not go back to the cheaper brands. The colours are fantastic, like watching an LCD TV. And having seen a large size on the wall from 80in to 100in diagonal, I do not like watching movies on my 42 inch Plasma.
However, Epson X31 has other issues.
(1) First, the resolution is too low at XGA (1024x768). The problem is not just about losing details in an HD picture but you can see the big pixels on the wall/screen which takes you out of the viewing experience. This is called the "screen-door effect" (SDE).
If going for this, I recommend at least going one model higher to Epson W04 which has a higher HD resolution of WXGA (1280x800) which will fall around Rs.42-45,000. The next model is U32 which is full HD WUXGA (1920x1200) for around Rs.52-55,000. However, the throw ratio is the worst in this model which means you need to keep the projector quite far to get the same screen size.
(2) Second, all "EB" models are business class products meant for data or presentations (or home entertainment vs home theater) which means they are meant to be watched in a bright room while accepting a washed out picture as something is better than nothing. But if watching with lights out, the brightness is too high which hurts the eyes. That doesn't work well for home theater users. You can use tactics like placing an "ND filter" lens made for cameras to reduce the light coming out or you can use a grey screen. Doing this felt like doing hacking and not expected after spending so much.
The next higher model is more suited to watching movies, which is EH-TW5300 but the cost is quite high at Rs.70-74,000. It also suffers from weaker blacks (as per reviews, I haven't tested it) which means a proper setup is required. But the throw ratio is excellent and the brightness isn't too high to blind you. You should only go for this if you have the budget for it. Don't over-stretch to get it.
Some other points from my experience:
Vivibright vs Egate: The corners in the Vivibright did not have focus. Egate seemed to have better focus in the center and the corners.
EGate vs Epson: LED projectors seem to throw out less heat. Having an Epson in the room meant that you had a small heater turned on which means in the hot summers you will need to keep the AC on and you will not be able sit too close to it. However, with regard to colours, Epson is more natural while Egate will feel like watching in black & white (used a light-yellow wall, may be better on a white screen, but not tested). But Egate had better blacks than Epson, maybe due to the lower brightness. That also meant easier on the eyes than Epson which is a light canon (but still not good enough even with one tube light on as any light in the room affects the picture quality). Epson has digital keystone which means you can place the projector off-center with some loss in picture quality which I didn't notice except on text. There is no "lens shift" feature in any of the models I have named here. The "throw ratio" of all Epson models are better than EGate (distance/1.55 = screen width) which means you get a bigger screen size for the same distance.
DLP vs LCD: I did not try any DLP projector as I was worried about the rainbow effect as I do get headaches even on watching TV for too long. The black levels are considered to be better here. But the bulb replacement costs are much higher.
Placement: Make sure that your eye level is at 30% to 50% of the projected screen from the bottom. That is, when you are seated, the screen shouldn't be too high up. Otherwise it becomes too uncomfortable to watch.
Screen size: Don't go for a projector unless you can go for at least 80 inch screen size which means a 70in width. For an immersive experience, I like the ratio of 1.35 the best (most people like it from 1.25 to 1.50). For example, if sitting at 120 inches away from screen, I would like a screen width of 120/1.35 = 89 inches (x 9/16 = 50 inch height). For a screen size of 89x50, the diagonal screen size will be 102 inches (formula: Pythagoras: a^2 + b^2 = c^2 where c is the diagonal size).
If going for Epson: Use Epson's calculators on UK/AU sites to get the proper estimates of screen size vs distance before buying any model. Also, buy from the local dealer for a better price than Amazon if you do not want the return option.
Darkness: For home theater use, you need to have darkness to enjoy the picture. However, I realized that my eyes start feeling tired too quickly due to watching flashing lights in a completely or heavily darkened room. The scientific reason for this is that the pupils have to keep contracting and expanding depending on the light levels in the room and the more it has to do that, the quicker the eyes get tired. Since I have to work for hours on a computer, I did not want to risk damaging my eyes. Not only that, I did not find it comfortable to watch and could notice that I am watching something instead of being lost in the movie. So I am out of projectors at this point but I do miss the immersive experience.
Future/Proper Setup: I probably shouldn't have gone casually into projectors with less time and budget as they are meant to be taken seriously if you are an AV enthusiast. If I go for it again, I will need to spend more time on setting up bias/ambient lighting by setting up a screen and placing lights behind it and some dim lights in more places. I will also need a grey screen, darker walls and a darker ceiling so that light does not reflect back on to the picture making it wash out by its own light. I will also need to do wall/ceiling mounting of the projector/screen to get perfect centering which means making it a fixed setup and doing a lot of hard work for it. That required a dedicated room which I didn't have and a lot of time and budget which also I didn't have at this time. I will probably upgrade to a 55-65 inch OLED TV first as it is easier for my eyes with all lights on.
Hope this helps someone. If anyone has found an easier solution or did their own testing, please share your own experiences on this forum. I found this forum quite useful when I was doing my setup.