Yep, im at the BC forums too :P.
Anyhow, to conclude this topic, most people will send their sets if politely requested, but please be understanding if:
-the person you are req. the set from is driving
-is fine tuning the team set
-is working on a set and is slower then default (has happened to me :P, car feels good but its slow, so i fine tune till i beat WR with a nice driving car)
-has blocked messages
-just plain doesnt want to share the fruits of his labour (working 5 hrs on 1 set is not unusual for me)