I too have been burning powder for longer than some on here have been around, started in the late 60's, early 70's with some junkers and as I could scrape together a few bucks upgraded over the years. I started going to Friendship when primitive was just a few lodges across the creek in the hollow, haven't been there in 25 yrs.
My primary flinter is now a custom built .45 cal with a 40" barrel. I never load more than 70 gr of FFF BP under a .15/.18 patch .440 RB. I know she will burn a lot more than 70 gr with that barrel length. She is very accurate and when I do my part she has never let me down.
The graybeards who taught me always stressed accuracy, the least amount of powder to do the job will give you less crud in the barrel,less recoil,less danger of damaging you or your rifle. They also stressed "tight in, tight out" in other words use the tightest possible patch/ball combo to get the tightest group. They talked how our forefathers went to small calibers, away from the large calibers of their fathers rifles, so they didn't have to carry as much powder and ball over the mts but still survive.
We will have disagree on the heavy loads but that is one of the beauties of shooting BP, to each his own. At the end of the day, as long as everyone is using safe loads in their rifles, we can all sit by the fire, look into the flames and dream of what it would have been like to live as those who carried hawk and horn many years ago.