The 5040 is rated at 2500 lumens by Epson but projectorcentral tested it at over 3500 lumens in it's brightest mode. At the very least, the difference in output isn't as large as the ratings would have you believe. The 5040 is one of the best values around. The only way I would go for a 3100/3700 over it is if the 5040 was out of my budget or if I was only concerned with viewing in ambient light or in a poor room (where contrast and black levels won't matter).
What to do if you find yourself stuck with no hope of rescue:
Consider yourself lucky that life has been good to you so far. Alternatively, if life hasn't been good to you so far, which given your present circumstances seems to be more likely, consider yourself lucky that it won't be troubling you much longer...
-- Excerpt from the Hitchhiker's Guide to the Galaxy.