Some people keep saying this, but I can hear a very clear difference.

It's like people who say that Arturia's VSTs are exactly like the real thing - to which I can only say "Huh???"

"differences" is not the same as "poor copies". You can even hear differences between different exemplar of the same analog synth, depending on components selection, calibration, age, etc.

Classic analog synths rarely sounded exactly like other copies of themselves. There was quite a large variation from device to device. I anticipate the Behringer stuff to be more consistent. As far as how close they sound it will depend on the particular example of classic synth you compare it to.