About BMW seats
M-Sport Models in Europe come with standard seats (pictured) or the Sport-seats as a no-cost option (also shown but not in the Platinum White Individual Trim pictured here!). Both standard and sport seats on the 6-series have electrical control for about 6-8 parameters and 3-memory function on the driver and passenger side. Additionally, you can option lumbar control on standard and sports seats as well without going to full 'Comfort Seat/Luxury Seat Package option (if you have a back issue or prefer this)
The Comfort Seats are marginally better - that is, you now have 20 individual settings with electrical control which i presume you will only ever use once to get comfortable. I really can barely if at all tell the difference. I also find the Comfort seats look heavier/bulkier so may suit certain body builds better, they seem to eat up rear leg room more than the standard and sport seats though.
All 3 BMW seats offer good support so I would not worry. I would worry a lot more about offset (a particular problem in Audis and some Mercs in RHD) to be honest. And for those of you aspiring to Maseratis and Ferraris, may I humbly suggest through personal experience that ALL their seats are pretty rubbish for support and offset.