Never had a problem with blood trails and BT, I've had a problem with too much blood from BT though. I have shot deer at 20 yards with the 308 and the blood was enormous, and so is the damage, even at 300 yards with my 300 win mag th damage is enormous. I'm tryng the Sciricco this year for this reason. I have seen a little difference between the every day BT and the ones from Combined Tech, seems the cap they place on the base causes the bullet to deform more rapidly but not fragment like the normal BT is known to do.
The matter of blood trails is very subjective, depending on where you hit you could have very little or tremendous blood, Hit high and fur could absorb alot of the blood, hit a little higher and it could hit the artery below the spine and could spray like a sprinkler. Hit in the middle it can pool up in the chest cavity, perferate the diaphram and it will pool in the lower abdomin. Not a very good measure of effectivness or bullet perfomance.