RE: Snap Roll and Rolling circle flight modes
I've done both. Ideally, you'd want just one flight mode for everything, but it depends on the aircraft design. For example, on my Focus, it would not snap well, do a hammer head well, or rolling circles well on just one rate. I had a rate for standard flying, a rate for snaps, spins and hammer heads, and a rate for one-roll circles and one-roll loops. The rolling circle rate was just for extra rudder, but the same elevator and ailerons as standard rate, to help with the one roll circles. The snaps, spins and hammer heads were for those manevuers, with expo increased on those flight modes to give the same feel around neutral. I could, for example be in the middle of a loop (just before an avalanch) with the elevator deflected, and perhaps some rudder in to correct for a cross wind, and hit the function switch and the plane would not jump with any difference in throw as compared to the inputs that were in place when I put the switch on. The toughest part about this setup is switching the rate switch at the end of a one roll circle from inverted. Its tough reaching for the switch when you have negative stick deflection entered.
Now the Brio, for example, is completely different. It has a lot of ruddder authority in standard rate, so I don't need a separate switch for hammer heads and one roll circles. I use one rate for them which is the same as regular flying rates. Same flying rate is good for one roll rolling loops also. I do use a separate rate for snaps and spins, but I'm right on the bubble, as the plane will do vertical down snaps on low rate for example. I still use the higher rates for more defined snaps. Its worth a point or 2 (or 10 in some cases).