Too much elevator effect will make it snap. Here is what I do: fly the airplane and gradually decrease the elevator control throw until you can pull full up elevator at speed without causing a snap. Use this as your low rate setting. If the elevator response feels sluggish at this reduced throw rate, then reduce the exponential rate to a lower level, lets say 0 to 20%. Be sure to do you test flying several mistakes high. You can then safely use this low rate setting to fly IMAC style aerobatics, pulling full up (and down !) elevator without fear of causing an unexpected snap. You can do a full throttle run on the deck and pull full up, all you will get is a loop, no surprise. On your high rate setting then use as much control throw as you want to fly pseudo 3D style stunts. Use a higher exponential setting here (eg 35 to 50 %) to prevent control over-sensitivity near the neutral position on the stick. Only use the extreme control throws of this setting when you are flying slower, this is the speed range where large control surfaces and extreme control throws come in handy without causing the plane to snap. Most aerobatic planes can be forced to snap by a sudden application of too much elevator at speed. This sudden change in the angle of attack of the flying surfaces causes turbulent airflow with abrupt loss of lift and control authority and wham ! ! you have got your snap. Setting up your low and high rates like this allows you to comfortably fly IMAC aerobatics to their limit and still be able to show off some 3d-like flying when you want. Just always be sure of which control rate you are flying on and adjust the speed accordingly.