My sister own a TSX with Navi, there are pros and cons to it. The Navi has never showed me a wrong position ever in 6 months...neither has it blanked out or anything but If someone is saying that the Navi is not at all faulty I dont agree, it has shown me directions every now and then when I am familiar with the road and know that I have to make a turn here (a major road) whereas it is taking me around (usually a longer way) but the thing is It takes you there so there is no way it will get you lost....

Another awesome feature that the Acura navi has which I havent seen in even Lexus or BMW Navi is the phone # feature where you just put the phone number of the person and it will I am guessing pull it out of the yellow pages or whatever and start showing you directions...

Also the Acura navi is DVD based so i am pretty sure acura guys are getting feedbacks and trying to get rid of all the bugs that their system have and come up with a new dvd some time (If you open the trunk there is a dvd player type thing from which you can eject the disc and put a new one)
so worst come worst you will have to spend a few bucks and update the dvd and you have a whole better updated navi.

so my point is if you have the extra 2K and are willing to spend it, go for it. its again the old battle of wants v/s needs.. another option just like leather seats (you dont need them to drive a car but you want them).