Hi there,
Wow your routine looks great! Very jealous
From 4am onwards babies start coming into light sleep more frequently. It's at that time that any sort of discomfort/hunger/other disturbances can lead to them waking up fully. Some things to think about - light? Noise? Heat/cold? Although he isn't always that hungry at 7am have you ever tried feeding at 4am when he first wakes to see if he has more settled sleep?
Do his naps always happen the way you listed or does he ever have short naps? Just thinking that overtiredness can be another cause for early morning unsettledness but I wouldn't have thought that was the culprit if he is napping as well as you said.
We don't support CIO here on the BW forums, so wouldn't recommend doing that. If LOs are truly independent sleepers then usually hard crying means a genuine problem. Have you listened closely to see what kind of cry it is? Is is an all-out 'I need you', tears etc kind of cry, or more of a fuss and whine? If it's a fuss and whine then it's ok to leave him, that's not CIO, and he may well fall back asleep without intervention. If it's an all-out upset cry though we would suggest you go to him. Maybe you could try shh pat instead of giving the paci?
My only other thought is that he may just need time to grow out of it, many mums report LO being quite unsettled in the early morning for no obvious reason. Reflux is sometimes thought to be a culprit - you could always try elevating the head of his bed to see if it makes a difference?