After reading enough posts now.... I've ruled out the Polaris. Now its between the Yamaha Grizzly 660 and the Honda Rubicon TRX 500. For riding extremly rocky trails and creekbeds with lots of brush, can anyone offer advice on which model might suit me best?  

the grizzly is a good machine and so is the rubicon, the only drawback to the rubicon is the electronic shift switches on the handlebars. they have had a bad habit of going out in the past so that it wouldn't shift.

so buy the extended warranty if you go with the rubicon.  

Thanks for the info. Tips like that are invaluable. We are narrowing down our search. It was interesting reading about the problems that the Polaris's have. Now I see why the salesmen at two different dealers were pushing them so hard. All the buzzers , bells and free give aways with the purchase of a Polaris ATV. (It's the same thing seadoo does to get you to buy their crap over a Kawasaki) One thing though,I was suprised to see how many of theses later model ATV's are still using carbs rather than EFI. Whats the deal with that? Also, does power steering really make that big of a difference on these?  

well to be honest i prefer the old carburetor over fuel injection.

for a few reasons,  they are easy to repair,they are inexpensive to repair, and still can be modified to perform as well if not better than injection.

if your injection goes out and your warranty is out as well, then you are left paying hundreds and sometimes a thousand or more to repair the atv.
there are advantages to fuel injection but the old carb is my personal preference.