Just received my second ACRO. Got both second-hand. Traded my 509T for this one. Right out of the box I appreciate the clear glass and crisp dot. The blue tint/notch filter on the 509T was driving me nuts in different lighting conditions. The 509T fishbowl magnification/distortion was unfavorable for me as well.
I will still probably buy a new improved version of the ACRO whenever it becomes available.