One of the big issues is the lie of projector numbers.
Lumen ratings are almost never anywhere near specification after a projector has been properly calibrated (ISF) for video. When you get good video blacks, proper whites and all the colors accurate, you find that most projectors for home use actually run closer to 500 lumens or so. Sometimes a little more - or slightly less.
But, they look phenomenal with video. They have very good scalers inside that tend not to allow motion artifacts on the screen. A lot of your money is going to pay for that processor so that video is smooth and clean.
This sounds like a bum deal, but you really have to get GOOD content and compare it side to side to see the difference. Stair stepping is when a diagonal line runs across the screen and looks all jerky instead of a clean straight line. A good home theater projector corrects that issue and makes it straight. A business projector almost NEVER includes that processing. Why should it? For your PowerPoint presentation?
All businesses want is a projector that can handle a few lights on in the room and a bright image.
Also, the technology with color wheels in home theater projectors is different than with business projectors. Business projectors usually include a clear section on their wheel to increase brightness. Home theater projectors usually don't, so color is better maintained and black levels are better.
Now, what you compared should be noted as two very different projectors.
The SP5000 is a NATIVE 16x9 projector at 1280x720 which means it's putting actual widescreen stuff up on the screen as it should be. It also is LCD instead of DLP which means we are discussing different categories altogether. The 3 chip LCD will never produce a rainbow effect which can be very distracting in video, and almost is never an issue in the boardroom with static displays. You will likely find a better lens on that SP5000 as well. The SP5000 also includes horizontal and vertical keystone correction, which likely isn't on the business model. No metion of whether it is just digital or optical as well.
Now, InFocus isn't exactly well known for the home theater projectors, though they do have some that are strongly recommended... But, the reality is that there are companies that really focus on making top notch video specific projectors that do so for a good price.
What you usually find on a home theater projector is that it includes the folowing features that many business projectors do not, and people are unaware of:
1. Designed to handle motion better
2. Black levels are better
3. Colors are more accurate
4. Vertical OPTICAL lens shift (very important that it is optical!)
5. Horizontal OPTICAL lens shift (sometimes) (also important to be optical!)
6. Quieter - sometimes dead silent. No obnoxious noise bothering viewers.
7. Better processing
8. Better optics
9. Native 16:9 ratio designed specifically for DVDs and HDTV - looks awesome!
Does that mean that 16:9 home theater projectors are always the way to go? No, of course not... But, to get the most out of a theater, you need a lot more than lumens to make a good picture.
In fact, it is very well known with theater installers that to many lumens is actually hard on the eyes. In a totally black room, ideal for film viewing, about 300-700 lumens is all that is necessary for a stunningly bright image. Your eyes simply adjust and do a marvelous job at it. So, it is everything other than lumen count that matters.
Likewise, when you get a digital camera, while megapixel count matters, if the color sucks, it eats batteries, and it is slow to take a shot then what makes the 5MP camera better than a 3MP camera that doesn't have all those flaws?
Anyway - not meant as a rant, but I have heard "What, I saw this projector that has twice as many lumens for half the price!" quite often. There is a reason it costs more from the same manufacturer for home theater... and it isn't about lumens.
