I contemplated the same thing and went with a base.
It depends on what $5,000 means to you, and whether or not you really need/want the features in the tech package.
If you're primarily interested in the back-up camera, I personally don't feel like its a feature that's worth the price premium alone. I test drove a lot of vehicles with back-up cameras, many of them better than what's used in the MDX, and it isn't anything that will eliminate the need to use your mirrors, or look over your shoulders (in fact most back-up camera systems will display a warning message telling you not to neglect your mirrors.) The back-up camera is useful for judging how close you are to an object directly behind you, which is useful, but still doesn't show you what's to the side/rear of your vehicle, like an approaching vehicle for instance.
The navigation in the MDX is very good, and worth the price premium if you utilize it a lot. If I still worked in outside sales the navigation would have been a must for me, but it certainly isn't anything I need now that I sit behind a desk all day.
The biggest draw of the tech package to me is the premium sound system, but I was less than impressed by it...esecially after hearing the Mark Levinson system in the Lexus. I'll probably install aftermarket speakers, but the I do like the fact that the tech's head unit can output in audio dolby prologic.
Those are the three main features of the tech package...again it depends on how much you feel you need them, and how much $5,000 means to you.