I'm not an actual pilot, but I do play a bit of DCS Black Shark, which is supposed to be as close as you can get to an actual helicopter. Of course, it's also a foreign helicopter with contra-rotating blades, so it's tough to compare some things from the sim to TOH. I think the biggest thing I've noticed is the ground effect is much more subtle in black shark, I have to really dump the collective to land in TOH. That combined with the weird rolling with collective for the medium and the odd lack of inertia I feel with the heavy are the biggest differences, I think.
I pretty much stick to the light chopper in ToH for now, it feels the most correctly implemented and handles nicely, and I've gotten used to sticking the landings through that ground effect with it.
I've also noticed the vortex ring stall is much easier to correct out of in TOH, this might be realistic, I just know if you do in in the Kamov, you often end up crashing anyway, or striking the rotor blades together (And crashing anyway).