I work with a business system and it's mainly OLTP but alot of long running adhoc queries goes on. So it's more like a combination with OLAP. Unfortunatley I never get the technician to turn off HT, but I measure SQL waits and in a rather large production environment I tried with MAXDOP 0 and MAXDOP set to the actual physical cores. And the last option gives the least amount waits. Even tried setting MAXDOP values between 0 and actual physical cores, but physical cores, still the best. Well, that's my experience.