I have the HT rad guard and I like it - it is necessary protection and a decent price and good quality. I didn't get the NERF bars because basically I got the bike used and it had already been dropped - nothing worth saving cosmetically. My only complaint about installing the rad guard was putting the reservior side on - it was a BEAR to get the holes lined up!!! Otherwise it is good stuff.
You need something there - you need to protect the radiator, fan and reservior in case you drop it. Nerf bars look like they do the best job - total cage protection but the good ones are pricey. You can also get an aftermarket tank that will cover the stuff, or you can just go with the rad gaurd inside the plastic.