I recently picked up the Mad Dog from Colemans based on several recommendations here. The sternum strap design is indeed a big improvement over the armpit harnesses out there.
I also came across this rig which is a sternum design too but more refined. Don't own it but thought folks here might find it interesting :)
http://www.youtube.com/watch?v=FAnLCKFr4eM
http://s4gear.com/products/lockdown/features
Two Sizes available:
LockDown for optics 6” to 7.5” in length.
LockDown Micro for optics 4.5” to 6” in length.
looks good, but I did not see a price
edj