The volume control on the back was a variation to the 1.07. There were some slight changes to the output stage but all the compressors were identical.
I have not heard of any comments about not liking the output control knob! The very early 1.05 compressors did not have output control. I fitted output controls on all compressors after the 1.07. I can assure you that in terms of compression, there is absolutely no difference between the 1.05 and the 1.07. The compression sound of all the early compressors right up to the last 2.2 was always the same. There were very minor variations on the range of attack and release times but they were basically all the same.