I'm pretty torn between the HD71 and the HD65, but I expect I'll be recommending the HD65, significantly more often. It's not that it is the better projector - technically, the HD71 is, as it is both brighter and has the faster color wheel. It's just that the HD65 works so well, right out of the box, and so few people really want to have to calibrate, tweak, or whatever you call it, their projectors. The HD65, is a great choice, and you can use it as is, or, better, I recommend you try dropping in the settings, that we came up with, and list in the General Performance page under Measurements and Calibration.
That should set you back all of 4-5 minutes, and will be well worth your time.
I should say, that the other reason I'll be recommending the Optoma HD65 more, is that, for those seeking the absolute maximum in brightness, will be choosing among four projectors, the HD71, Panasonic PT-AX200U, Mitsubishi HC1500, and Epson Home Cinema 720.
Now, keep in mind, the HD65 definitely competes, and is actually as bright or brighter than the two 3LCD projectors above (Epson and Panasonic) when all are in best modes. However, all four of these others are significantly brighter when you need all the lumens you can find, for that sporting event, or handling more than a reasonable amount of ambient light.
Optoma HD65 as a Business Projector
The HD65 has a couple of things going for it as a crossover projector. First, it's about as small as home theater projectors come, and weighs in at 4 pounds (1.8 Kg.), making it a reasonably small portable projector. With brightness up to almost 1200 lumens (measured), it's not much dimmer than most of today's entry level projectors which claim 1800 - 2000 lumens, and like the Optoma, will also typically produce 10-25% less lumens than claimed. It certainly has enough horsepower for the typical conference room with moderate lighting on screens up to 6 feet diagonal, and 10 foot diagonal will work fine if lighting is low.
It lacks a speaker, but that shouldn't be an issue for most, as the sound from most 4 pound and under business projectors is barely better than what is found on most laptops, and a far more powerful small portable speaker could be bought if needed.