Hmm, never thought about doing an auto from a climb? There's something to bring up next time I go to the safety course.
Don't tempt fate, Butters, the aircraft has vertical momentum and lots of pitch pulled. When the engine quits, you have further to shove the lever down, and it takes longer for the upwards momentum (airflow coming from top) to convert to downwards flight (airflow coming from below) and the RRPM will decay so much more.
For that reason, most single-engine helicopters have a rate of climb limitation of 2000'/min. Not something that worries an R22, but 407 and the like can easily do it when light.