I wouldn't say that NOTAR doesn't auto so good, but I would probably say that the USBP 600's and maybe even all 600's don't auto so good. I did not find them unpleasant at all to autorotate (to touchdown and up to max internal gross weight) in. One thing that has changed in recent years is the MR blades. There is signifigant differences in the lift capability and the autorotation charachteristics of a 369, 500N or 600N with blades produced by HTC (current factory blade) and the blades that were produced by Boeing (and before that MDHI or Hughes).
The 600 was an eye-opener the first time you did an auto, but once you learned the techniques was not a problem. You definatly did not want to doze off while flying though- you have to stay on your game.
Remember, in true autorotation you are not using anti-torque, only at most a little anti-friction. Guys that bitch about yaw at the bottom are landing with the engine driving the rotor (maybe the technique needs improved) or doing a power recovery (probably from a lower than 100% NR) If the NR is above 100% when you join the needles, you won't get a yaw. If you touchdown without the engine driving the rotor you will not get an uncontrollable yaw either.
The USBP disliked the 600 for more than just autorotation charachteristics. The biggest problem was trying to replace the beloved OH-6A with the 600. Too different of animal to compare. After you get a firm dislike for something, anything is better and it is hard to change minds that are made up.
There is such a thing as NOTAR, it is even trademarked! You are correct, NOTAR does not work at altitude, I have never landed or hovered above 12,500 Hd feet in a NOTAR (MD902 and MD600). But up to 12,500 I can say it worked every bit as well as tail-rotor machines I have flown at comperable weights.