I have been an Alfa guy since I saw my first GTV back in 1973. I finally bought my first one in 85 or 86. That is the one I still own. I have had several of them as DD until they got to be big $$ cars. The 4C is a great car. My wife is not thrilled with the suspension or the exhaust volume. Long distant trips are tiresome for us old folks. I agree that it is certainly a modern equivalent to the X1/9.
I know well about slow as I have an 850 coupe that I have been debugging. The X will feel supersonic compared to that.
The X1/9 hopefully will give us a nice little vintage vehicle that we both will like. The one I am buying has 21k miles on it. The current owner has had it for 6 years and put about 5 k miles on it. From the pictures ans video chat it looks to be an honest low mile car. It is from Texas and appears to have no rust. It is not perfect but as this group knows, those are few.
I enjoy driving and look forward to the new experience.