While you lost me with that explanation, I do agree that the flybar does rate P.
Tim, just be careful with that. You might be able to hover it. But I doubt it's actually flyable, at least not very well. Take it out and slam it around a little bit and you're likely to lose control of it with the rates set close to the defaults.
The basic tuning procedure is to turn off the rate I and D and turn up the P until it gets unstable, then back it off to where it seems stable. Then adjust the VFF to get decent control response so you can actually fly it. Then turn up the rate I up to about .15 or so to start. Most people don't run any rate D with helicopter with FBL.
Then I would fly it awhile and slam it around a little bit. Slam it into the ground hard and lift off again and see if it upsets it. Fly it around trees in gusty wind. Hover it sideways and scrape a skid and see if it goes into roll shakes. Take it out and make a couple high speed passes with it to see if stays stable. That gives you time to tweak it and get used to it, look at the logs and see if there's any problems, etc..
Then try Alt Hold once and see if it holds altitude ok. If it does, try Loiter, and turn up the I gain until it seems to hold position pretty well in the wind. Just be aware that in Loiter it is sluggish. Loiter is not designed to be flown at very high speeds or any sharp moves. It is more of a stationary hovering mode. There's some adjustments you can make to Loiter to make it "sharper" on handling though.
I don't know if Position Hold works in helicopter or not in the latest code. I crashed one 600 with Position Hold before and I consider it a "bad" mode for helicopters. It tries to use the rates in Alt Hold when you move the sticks, and change back to Loiter when you let go of the sticks. I think it was invented to try to compete with DJI with the way their "GPS-Safe To Fly" stuff works. It might be the best thing since sliced bread for multi's, but it doesn't actually let you fly a helicopter - it's a wonked up mode if you ask me. I don't recommend using it, but you can if you want, at your own risk.
As far as vibration, it's just like any FBL unit. The less you have, the better it will work. I guess the "guideline" is about +/-3 on X and Y and below 15 for Z for really good performance in Loiter. Mine are all higher than that and yet they seem to fly pretty well. I think the guideline on Z vibes is that it has to be below about 25-30 or it will have problems holding altitude.