I Downloaded 1.6++ straight from LazyZero's flash tool. Just another one of the roms available.
I've said it before, chicks dig helis . . . but crashes? not so much.
There are fundamental diffrences in how the control is interperated between the two modes, but I'm only vaugly familiar with the guts.
IIRC, SL stick position equates to target angle off of level, where acro stick position equates to target angle *rate* off of not rotating. Since "angle" is measured by a accelerometer reading (it's just a number), a high scaling, high throw command could litteraly equate to "go to 270 degrees", at which point, if you get there before finding the ground, the copter is 3/4 flipped when you release the control and it seeks the fastest way back to level.
In that case, SL will be twitchy as all get out, so you'll need expo, then acro starts needing higher adjustments to keep ahead of (making it harder to use). If the scaling isn't set high enough, however, it doesn't matter how far the copter can fall, it will never go much past the target angle in SL and therefore will never flip.
Frankly the accelerometer/gyro "mix" idea in 1.6++ really works well -- very controllable and stable on medium/high rate with great roll/pitch authority. Multiwii has it's own selection of modes, and mixtures thereof, combining not just the gyros and accelerometers the KK2 has, but barometers, compasases and GPS's into the control mixs as well. Those, however I've only heard of, but don't understand.