Just thought I'd put my 2 cents worth in. I'm roughly 6 foot, 80kgs.
I've had a pair of Recaro Speed's in my daily. I drove 1800kg straight from Melb to Brisbane in it. Not too bad, but my backside got a numb after a few hours. The base of the seat really holds your legs in place, however, for me, the upper half of the seat just didn't have the same amount of hold. By torso seemed to sift about the seat through corners. I still have them in the daily, but I'm glad I'm moving onto a luxo car with leather....
I had a pair of OBX Daytona's in my play car, but was not overly impressed, besides the fact that they are ADR approved. I bought mine new years ago. I found the the base lacked decent support and the backrest encouranged hunching over. I would end up with bad lower back pain for a trip from Melb to Winton. I got my hands on some foam inserts, but it was still not that great. The thigh support was too big, causing me to have the seat closer to the steering wheel. My clutch leg would get stiff and sore after a few laps.
I've just purchased a pair of Sparco Junior's. After sitting in them, they would instantly be the better of the 3 seats. Not as narrow as the OBX, but better torso support than the Recaro Speed's. Shoulder support is great, without pushing your shoulders forward (which is what I found the OBX seats did). I'm looking forward to getting them into the car and taking them for a test drive........ or sit.