We had a little contest in our club to see if there were any advantages either way.
The people with loose powder used quick loaders the people with pellets used what ever way the loaded while hunting, the first contest was for speed and 3 shots.
The loose won by 20 seconds.
The second contest was for accuracy, 10 shots from the bench at 150 yards the loose team won again by a whole 100 points, the value of one full target.
There were 3 people on each team who are normally equally matched on our normal shoots.
We realize that every body has good and bad days and that the ways of loading might be improved on by something we do not know. I was one of the people using loose and I have tried both and it came out about like I expected. Most of the people that use pellets either don't shoot a lot or are beginners; that by it self should tell you something.