Now, I have figured out, I think, the handling difference in the MicroHeli head.

First let me say that the stock Bell-Hiller head on my BCPP is tuned to the max, damping is tight, it is extremely smooth, the helicopter is stable and responsive with it, climbs out well. I'm no 3der but I imagine that this stock head (with the EFlite aluminum swash with big Align servo link balls but no other mods) is working about as well as the stock head can work.

The MH head is better. It handles better. At first I didn't think so. But now that I have it tuned up and with a better pitch curve, it is better. The Bell-Hiller mix ratio is different than the stock head. With the stock head, it's like reverse expo or something, the cyclic is verrry sensitive right at center stick, you get most of the responsiveness with tiny deflections, and the response tapers off as you move the stick more toward the stops.
With the MH head, I was actually able to watch the flybar control the rotor disk, and if I deflected aileron, say, 15 degrees, the rotor disc tilted 15 degrees. Elevator the same way, the response of the helicopter rotor disc seemed to exactly follow the amount of stick deflection. Really neat. It makes the controls seem a lot more sensible somehow. And of course you get full responsiveness, it just happens at a more logical place--near the ends of the stick travel rather than just off-center.
I'm exaggerating for effect of course, the difference isn't that great, it took me several packs to figure it out. Definitely better though.

The only programming change I made was a calmer idle-up pitch curve. I'm still using no expo and 100% travel on the cyclic controls, just like with the stock head.
I tried expo before when I first started flying this heli, and used it for a few days until I found I could calm down enough to fly without it in spite of the "twitchyness". Now I think it would be bad, with this head you really don't need it.

And some data:
Flying weight 408 grams, a 1320 mAh 13C battery and the Hacker 4900kV brushless main, the GWS DD tail.
Idle-up flight mode, heavy swooping, as much cyclic workout as I could manage in my pad, gyro/tail stress testing.
Start: 1753
End: 1808
that's 15 minutes. So I don't think the brushless main/DD tail reduces the flight time very much. I was glad when the battery ran out, I needed a shower and a beverage.