For tall or large people:
The 3-doors has more shoulder room, because the b-pillar is more backwards.
In a 5-door, I felt confined and restrained, and my shoulders were pressed against the b-pillar. In a 3-door, I didn't have this problem.
I read on the German 1-series forum that a lot of tall people choose the 3-door just for this.
(I'm like 1m96, or 6 foot 5 inch)
I drove with an E92 with frameless door for 4 years, and never had a problem. But winters in Belgium are not as harsh as in Norway I suppose. We get like -10 °C here. No issue with that with the frameless door.