Just adding something about my experience with Mini. I’m a neurosurgeon so I wear scrub all day and the mini fit gorgeous in each pocket (front or rear pants pocket, front shirt pocket, in the white coat), no need to distress about fell away during the journey. The same with all of my jeans and pants and all of my suits (stealth in the internal pocket of suit’s jacket).
About screen size: for me, it’s good. If I want to watch or read more than an email or some forum’s messages, I use my iPad.
Battery: my daily routine is one hour trip by car to reach work and one hour trip to come back home. During this time my Mini is on charge and in use with Apple Car Play. Never had any problems during working day with battery. Tested it in few occasions outside (trip to seaside, with photo and some browsing and texting all with high brightnes) and able to came back home in the evening with 40-50%.
Material: the aluminium is, in my opinion, better than SS because is really lighter and less prone to fingerprint (I always finish with using my iPhone naked).
I think that this mini is something like the X that I want instead of the X that Apple made. Anyway I’m totally satisfied by it.