I helped run a bear camp in NW Manitoba for 16 years I was on a lot of blood trails and I can tell you lots of stories but from what my experiences were, don't use a two blade . Beas are easy to kill and a good double lung will usually go down with in 30 yards, but not always, we had some go further some more than 150 yards. In the thick bush you need a blood trial and a lot of the times with the 2 blade you wont get it .
It was in the 80s and 90s when I was there and thunderheads in 3 blade were popular and they worked great good blood trails. Some of us used 125 grain Snuffers they were probably the best.
My wife used a Bear Razorhead and the last bear she shot with here 45lb. longbow she got a pass through and the arrow was stuck about 6 inches into the ground . Bears have thin skin and small ribs they are easy to shoot through don't worry about penetration with good arrow placement, but if you hit the heavy bones of the shoulder it doesn't matter what rig you have your not going to get through. If you get a marginal hit a big three blade is best .