interesting perspective. i usually abstain from mixing chems that have this mcuh of a difference in duration (2ci is a long trip for me, while mdai is 3h max). could you maybe compare it to a normal 2ci trip experience at the same level for you? so as to show what the mdai brought?
You're in luck. I had used the exact same dose of 2C-I a few days before I tried the combo. Through out the experience, I was taking mental notes of the differences. Regarding the difference in duration, I would recommend taking the MDAI a few hours after the 2C-I so they end at about the same time. MDAI tends to last 4-6 hours for me and 2C-I lasts 7-9 hours in my experience. When I did the combo, I took both at the same time and had a decent amount of trip left over once the MDAI wore off. It wasn't bad though.
Anyway, the differences between the combo and 2C-I alone. Both were done with my group of friends, some of whom were using the same drugs as me:
Adding MDAI made it a much more social experience. Talking was easy and natural. When I was on just 2C-I, conversation was doable but kinda awkward. I would start sentences and then trail off. With the MDAI, I was talking a mile a minute, as I usually end up doing with serotonin releasing drugs. Along the same lines, the combo brought what I call the "hug effect" on the people using it. Like, it makes you go around asking for hugs and you start complementing everyone in the room. Ya know, that wussy empathogen feeling that we all seem to love so much

When I was only on 2C-I with the same people a few days before, no one was hugging anything or talking much. I was afraid that the MDAI would get "drowned out" so to speak, but I'd say the two were about equally noticeable.
Adding MDAI also made the trip a little more grounded in reality. IMO, 2C-I never really brings you that far from reality, but while the MDAI was working, the world didn't seem fucked up at all, save for everything wobbling and purple globs shooting across the ceiling

However, when the MDAI wears off, it can be a bit shocking. One of the people I was doing this with had to take a few minutes to gather himself once he realized how hard he was tripping 5 hours after dosing. That's why I recommend giving the 2C-I a head start.
All and all, it was a great combo that I will definitely do again. I basically spent the night with a goofy grin on my face while alternating between socializing with my friends and staring at the ceiling. We also had an interesting game of jenga, which went surprisingly well considering the tower was moving the whole god damn time. At the doses I used, the two drugs seemed to coexist evenly. The reason I tried this combo was because when I use just 2C-I, it brings a physical rush like MDMA does for me but with a different headspace. MDAI brings the mental feelings of MDMA but without the rush. When put together, it is kinda like rolling but with some cool visuals to go along with it. There isn't much not to like.