Actually not, if you ever read reviews and scientific buff at the time sir.. ABR's can and did flap about if they weren't under proper control. Why do you think only a very few people used this technology?

You don't get owt for nowt and the phase situation was a "joy" I understand, although sonically not too much of an issue (driver goes in, ABR pumps out and there'll be a frequency when they sort of blend and the ABR stops working)