Interesting review. One thing I would say is to check the tire pressure - BMW seem to set the recommended pressure quite high - I think its something like 2.7 bar at the front. I've knocked this down to 2.5 and the ride is much more compliant. But still firm vs the GTD for sure.
I know where you're coming from re the seats and sitting 'on them' rather than in them. That said its taken a while to find the perfect seating position but I've found by tilting the seat base a little they are very comfy (for me anyway). The adjustable side bolsters on the seat back are great as well. I also like the way the back of the seat curves up a little so your head is very close to the headrest. I guess they could have done better with the seat base - but did a great job with the backrest.
I'm pretty sure you can spec a spacesaver for the 1 series as well - could be wrong on that.
I looked at the TPMS.... was 2.2 on the rears and 2.9/2.8 on the front.... wasn't my car so wasn't about to start letting air out.
The seat I spent about an hour messing around with. I opened up on the online manual (really nice feature I didn't mention yestrerday but I thought it was brilliant) and adjusted every aspect of the seat. Nothing doing.
Did spot a weird thing though, the passenger seat is different to the drivers seat.... I could make the passenger seat comfortable.... bit far to reach the pedals though.
I'm sure its just me, but it did really remind me of the F56 or R58 we have on the drive (amongst others!) - I can drive them, but not far without back and hip pain. I try not to use them if I can.