Hello. I am an avid fixed wing pilot (I fly in pattern competition and instruct beginning pilots) but am completely new to helicopters. This spring I am planning to purchase a 400 - 450 sized electric helicopter, so I am practicing on RealFlight G3.5. I am able to hover, fly around, go into stunt mode and perform inverted hovers, loops, and a few other things (including turning up the wind) comfortably. From flying fixed wing, I understand that the simulator doesn't give the complexity of model flight its full due. What are the major differences between the simulator and real life that tend to trip up beginning helicopter pilots.

Thanks!

everything
theres no subsatute for real flight
and your not wooried to crash on a sim.but when you fly the real thing thats all you think about
i can do anything and everything on a sim. but with the real heli im doing good to hover and forward flight

Well first of all, the helis in the sim fly based on a 'perfect' mechanical set-up. Most people when first starting out (myself included) rarely have their heli set up perfect due to lack of experience, so your real one likely won't be as stable.
Also the larger the heli the more stable it will be so it is best to practice with a model that is the same size as the one you fly or plan to buy.
And as mentioned above you tend to be more relaxed when flying the sim since a push of a button after a crash and you are set to go but will be more tense when flying the real thing. Of course since you instruct new fixed wing pilots you probably see how nervous they can get when learning to fly the real thing. ( Generally referred to as the 'pucker factor')

I got my first heli the end of Oct 08. The helimax CPv3 and can hover it OK now. The cold weather here has slowed my progress.
I also have the RealFlight G3.5 which I can do a lot of things with but not with the real heli. I think as a beginner the biggest difference is the real heli is so much quicker than the sim. It's also very easy to get disoriented with the real heli. After a long time on the sim it seems to get or be predictable. Not so with the real heli.

Since you plan on a 450 size, the best way to train on the sim is to use the Axe CP, turn the gyro gain down a bit, and turn the physics speed up to 110%. Use a smaller less stable heli, and crank the speed, and when you get that one down, as long as you take your time on set-up, and preferably have someone experienced help you, and follow Radd's, you should have little to no problem going to a real 450 heli.

Thanks. Upon reflection, I suppose my question was how to set up the simulator so that I can best practice. I think that has been answered well.

Thanks again.