I do think every parent has a right to do what they feel is best for their child but I too would be concerned that maybe the CC has caused some distress and maybe your DS is now scared of the cot/sleep?
My son has terrible sleep issues and I went for a day stay at tweddle (sleep school in Vic)
My husband and I hated it. DH refers to it as baby prison camp! We were not even officially doing CC due to Logan's age but he spent most of the day screaming.
Was awful and I will never do any form of CC even if it means I lose a lot of sleep. Personally, I can't see how it can't have some lasting impact on the child but then I do understand a perent's desperation for something to work and for some it probably does.
I don't think there is any "blanket" formula that fits ALL children - they all have individual personalities.
Anyway, if you don't want to resort back to letting him cry to sleep, maybe try a gradual weaning of the rocking eg rock until he is drowsy then put him down, if he screams - pick up and try again. Each night make the length of rocking shorter and putting him in cot more awake. May take some time but just a suggestion.
May also help to let him have play time in the cot so it is a fun place for him