At your price point, your options are fairly limited. At that budget, I’d get the 4000. I recently read a thread at AVS where someone had access to a Sim 2 Lumis and the 4000. He installed them both and was very surprised that the gap in performance between the two was not nearly as large as expected (keep in mind that the Lumis is a + $20,000 projector that the majority of videophiles consider the holy grail of digital projectors). This little experiment just goes to show how far digital projector performance per dollar has gotten the last couple of years. It seams as if $2000 will get you about 85% of the way to “best performance possible”, and you have to pay through the nose to get marginal improvements above 85%. Here’s the thread - http://www.avsforum.com/avs-vb/showthread.php?t=1206133
Considering you have a light controlled room, go with a white screen. Grey aids in rooms where stray light is an issue, or rooms in which you want to have light present. The screen reflects whatever light is present in the room, including stray light from sources other than the display device. Grey tends to reject stray light, which in turns improves overall contrast. However, grey detracts from shadow detail. This is also why it is recommended to paint your walls and ceiling flat black, and preferable to use black velvet. By painting flat black or using black velvet, stray light is not reflected to, or from the screen. This may seem overly fussy, but if you’ve ever tried to take ANSI contrast readings, you will soon understand just how important this is. ANY stray light in the room, regardless if it is reflected to the screen or from the screen into the room has a negative effect on ANSI contrast. ANSI is what gives that POP and 3D look that everyone wants. You can improve shadow detail if the display allows you to tweak the gamma curve, but unless you want to invest in the equipment to calibrate the machine, you will be stuck picking out a pre-programmed gamma curve and these tend to come with compromises. At your price point, you’d be better off just sticking with a white screen with a neutral gain and use one of the pre-programmed viewing modes that appeals to you the best and don’t mess with calibration. Once you head down the road of calibration, you might as well suck it up and zero out your checking account because you will never be happy. – I speak from personal experience.
High gain screens come with penalties. Because of the screen make up and the method in which they reflect an image brighter than the source of light, you will see hot spots, sparkles, and have a narrow viewing cone. Most also require the project to be specifically mounted either above, or below the screen at a particular offset, and if you deviate from this, the result is a negative gain. From what I have read, Carada appears to have the best screen on the market right now under $1000. Stewart is arguably the best, but you pay for them. You can attempt to make one yourself, but it’s doubtful that whatever you make will perform as well as the Carada. I suppose it really comes down to how much your time means to you and how picky you are.