Neuspeed or Racing Dynamics springs

Has anyone used Neuspeed or Racing Dynamics springs on their 540i sport (e39) or other e39? There is a lot of information out there about H&R, Eibach and Dinan but nothing on Neuspeed or RD springs. I have an opportunity to purchase either and don't know which is better. Any help would be great. Also, I noticed that H&R has a different fitment for the standard 540i and the sport. Anyone know why H&R has this and no one else does?